diff --git a/core/trace/carrier.go b/core/trace/carrier.go
index 004ace7f..4308b8a9 100644
--- a/core/trace/carrier.go
+++ b/core/trace/carrier.go
@@ -6,9 +6,11 @@ import (
 	"strings"
 )
 
+// ErrInvalidCarrier indicates an error that the carrier is invalid.
 var ErrInvalidCarrier = errors.New("invalid carrier")
 
 type (
+	// Carrier interface wraps the Get and Set method.
 	Carrier interface {
 		Get(key string) string
 		Set(key, value string)
diff --git a/core/trace/propagator.go b/core/trace/propagator.go
index 32ebf727..9d18979d 100644
--- a/core/trace/propagator.go
+++ b/core/trace/propagator.go
@@ -7,7 +7,9 @@ import (
 )
 
 const (
+	// HttpFormat means http carrier format.
 	HttpFormat = iota
+	// GrpcFormat means grpc carrier format.
 	GrpcFormat
 )
 
@@ -17,6 +19,7 @@ var (
 )
 
 type (
+	// Propagator interface wraps the Extract and Inject methods.
 	Propagator interface {
 		Extract(carrier interface{}) (Carrier, error)
 		Inject(carrier interface{}) (Carrier, error)
@@ -58,6 +61,7 @@ func (g grpcPropagator) Inject(carrier interface{}) (Carrier, error) {
 	return nil, ErrInvalidCarrier
 }
 
+// Extract extracts tracing information from carrier with given format.
 func Extract(format, carrier interface{}) (Carrier, error) {
 	switch v := format.(type) {
 	case int:
@@ -71,6 +75,7 @@ func Extract(format, carrier interface{}) (Carrier, error) {
 	return nil, ErrInvalidCarrier
 }
 
+// Inject injects tracing information into carrier with given format.
 func Inject(format, carrier interface{}) (Carrier, error) {
 	switch v := format.(type) {
 	case int:
diff --git a/core/trace/span.go b/core/trace/span.go
index 7c73f39c..bdbf0af0 100644
--- a/core/trace/span.go
+++ b/core/trace/span.go
@@ -21,6 +21,7 @@ const (
 
 var spanSep = string([]byte{spanSepRune})
 
+// A Span is a calling span that connects caller and callee.
 type Span struct {
 	ctx           spanContext
 	serviceName   string
@@ -58,9 +59,11 @@ func newServerSpan(carrier Carrier, serviceName, operationName string) tracespec
 	}
 }
 
+// Finish finishes the calling span.
 func (s *Span) Finish() {
 }
 
+// Follow follows the tracing service and operation names in context.
 func (s *Span) Follow(ctx context.Context, serviceName, operationName string) (context.Context, tracespec.Trace) {
 	span := &Span{
 		ctx: spanContext{
@@ -75,6 +78,7 @@ func (s *Span) Follow(ctx context.Context, serviceName, operationName string) (c
 	return context.WithValue(ctx, tracespec.TracingKey, span), span
 }
 
+// Fork forks the tracing service and operation names in context.
 func (s *Span) Fork(ctx context.Context, serviceName, operationName string) (context.Context, tracespec.Trace) {
 	span := &Span{
 		ctx: spanContext{
@@ -89,14 +93,17 @@ func (s *Span) Fork(ctx context.Context, serviceName, operationName string) (con
 	return context.WithValue(ctx, tracespec.TracingKey, span), span
 }
 
+// SpanId returns the span id.
 func (s *Span) SpanId() string {
 	return s.ctx.SpanId()
 }
 
+// TraceId returns the trace id.
 func (s *Span) TraceId() string {
 	return s.ctx.TraceId()
 }
 
+// Visit visits the span using fn.
 func (s *Span) Visit(fn func(key, val string) bool) {
 	s.ctx.Visit(fn)
 }
@@ -126,6 +133,7 @@ func (s *Span) followSpanId() string {
 	return strings.Join(fields, spanSep)
 }
 
+// StartClientSpan starts the client span with given context, service and operation names.
 func StartClientSpan(ctx context.Context, serviceName, operationName string) (context.Context, tracespec.Trace) {
 	if span, ok := ctx.Value(tracespec.TracingKey).(*Span); ok {
 		return span.Fork(ctx, serviceName, operationName)
@@ -134,6 +142,7 @@ func StartClientSpan(ctx context.Context, serviceName, operationName string) (co
 	return ctx, emptyNoopSpan
 }
 
+// StartServerSpan starts the server span with given context, carrier, service and operation names.
 func StartServerSpan(ctx context.Context, carrier Carrier, serviceName, operationName string) (
 	context.Context, tracespec.Trace) {
 	span := newServerSpan(carrier, serviceName, operationName)
diff --git a/core/trace/tracespec/spancontext.go b/core/trace/tracespec/spancontext.go
index 4c140837..cb91d888 100644
--- a/core/trace/tracespec/spancontext.go
+++ b/core/trace/tracespec/spancontext.go
@@ -1,5 +1,6 @@
 package tracespec
 
+// SpanContext interface that represents a span context.
 type SpanContext interface {
 	TraceId() string
 	SpanId() string
diff --git a/core/trace/tracespec/trace.go b/core/trace/tracespec/trace.go
index 74db6ff7..b0576ce2 100644
--- a/core/trace/tracespec/trace.go
+++ b/core/trace/tracespec/trace.go
@@ -2,6 +2,7 @@ package tracespec
 
 import "context"
 
+// Trace interface represents a tracing.
 type Trace interface {
 	SpanContext
 	Finish()
diff --git a/core/utils/times.go b/core/utils/times.go
index 8d03e266..aeec03bb 100644
--- a/core/utils/times.go
+++ b/core/utils/times.go
@@ -7,32 +7,39 @@ import (
 	"github.com/tal-tech/go-zero/core/timex"
 )
 
+// A ElapsedTimer is a timer to track the elapsed time.
 type ElapsedTimer struct {
 	start time.Duration
 }
 
+// NewElapsedTimer returns a ElapsedTimer.
 func NewElapsedTimer() *ElapsedTimer {
 	return &ElapsedTimer{
 		start: timex.Now(),
 	}
 }
 
+// Duration returns the elapsed time.
 func (et *ElapsedTimer) Duration() time.Duration {
 	return timex.Since(et.start)
 }
 
+// Elapsed returns the string representation of elapsed time.
 func (et *ElapsedTimer) Elapsed() string {
 	return timex.Since(et.start).String()
 }
 
+// ElapsedMs returns the elapsed time of string on milliseconds.
 func (et *ElapsedTimer) ElapsedMs() string {
 	return fmt.Sprintf("%.1fms", float32(timex.Since(et.start))/float32(time.Millisecond))
 }
 
+// CurrentMicros returns the current microseconds.
 func CurrentMicros() int64 {
 	return time.Now().UnixNano() / int64(time.Microsecond)
 }
 
+// CurrentMillis returns the current milliseconds.
 func CurrentMillis() int64 {
 	return time.Now().UnixNano() / int64(time.Millisecond)
 }
diff --git a/core/utils/uuid.go b/core/utils/uuid.go
index 237235db..3fa80829 100644
--- a/core/utils/uuid.go
+++ b/core/utils/uuid.go
@@ -2,6 +2,7 @@ package utils
 
 import "github.com/google/uuid"
 
+// NewUuid returns a uuid string.
 func NewUuid() string {
 	return uuid.New().String()
 }
diff --git a/core/utils/version.go b/core/utils/version.go
index 9f98adc7..ad1ded8c 100644
--- a/core/utils/version.go
+++ b/core/utils/version.go
@@ -14,7 +14,7 @@ var replacer = stringx.NewReplacer(map[string]string{
 	"-": ".",
 })
 
-// operator compare returns true if the first field and the third field equation holds else false
+// CompareVersions returns true if the first field and the third field are equal, otherwise false.
 func CompareVersions(v1, op, v2 string) bool {
 	result := compare(v1, v2)
 	switch op {