diff --git a/weed/shell/command_s3_configure.go b/weed/shell/command_s3_configure.go
index ddcafd847..c3c0a0d34 100644
--- a/weed/shell/command_s3_configure.go
+++ b/weed/shell/command_s3_configure.go
@@ -2,6 +2,7 @@ package shell
 
 import (
 	"bytes"
+	"errors"
 	"flag"
 	"fmt"
 	"github.com/chrislusf/seaweedfs/weed/filer"
@@ -164,6 +165,17 @@ func (c *commandS3Configure) Do(args []string, commandEnv *CommandEnv, writer io
 		s3cfg.Identities = append(s3cfg.Identities, &identity)
 	}
 
+	accessKeySet := make(map[string]string)
+	for _, ident := range s3cfg.Identities {
+		for _, cred := range ident.Credentials {
+			if userName, found := accessKeySet[cred.AccessKey]; !found {
+				accessKeySet[cred.AccessKey] = ident.Name
+			} else {
+				return errors.New(fmt.Sprintf("duplicate accessKey: %s, already configured in user[%s]", cred.AccessKey, userName))
+			}
+		}
+	}
+
 	buf.Reset()
 	filer.ProtoToText(&buf, s3cfg)