diff --git a/weed/mq/kafka/consumer/group_coordinator.go b/weed/mq/kafka/consumer/group_coordinator.go
index ed18cded1..e7e8eab3f 100644
--- a/weed/mq/kafka/consumer/group_coordinator.go
+++ b/weed/mq/kafka/consumer/group_coordinator.go
@@ -1,6 +1,7 @@
 package consumer
 
 import (
+	"crypto/sha256"
 	"fmt"
 	"sync"
 	"time"
@@ -187,11 +188,12 @@ func (gc *GroupCoordinator) ListGroups() []string {
 	return groups
 }
 
-// GenerateMemberID creates a unique member ID
+// GenerateMemberID creates a deterministic member ID based on client info
 func (gc *GroupCoordinator) GenerateMemberID(clientID, clientHost string) string {
-	// Use timestamp + client info to create unique member ID
-	timestamp := time.Now().UnixNano()
-	return fmt.Sprintf("%s-%s-%d", clientID, clientHost, timestamp)
+	// Use hash of client info to create deterministic member ID
+	// This ensures the same client gets the same member ID across calls
+	hash := fmt.Sprintf("%x", sha256.Sum256([]byte(clientID+"-"+clientHost)))
+	return fmt.Sprintf("%s-%s-%s", clientID, clientHost, hash[:8])
 }
 
 // ValidateSessionTimeout checks if session timeout is within acceptable range
diff --git a/weed/mq/kafka/protocol/joingroup.go b/weed/mq/kafka/protocol/joingroup.go
index 84b2060ad..770f85825 100644
--- a/weed/mq/kafka/protocol/joingroup.go
+++ b/weed/mq/kafka/protocol/joingroup.go
@@ -101,11 +101,33 @@ func (h *Handler) handleJoinGroup(correlationID uint32, apiVersion uint16, reque
 	// Handle member ID logic
 	var memberID string
 	var isNewMember bool
+	
+	// Use deterministic client identifier based on group + session timeout + protocol
+	clientKey := fmt.Sprintf("%s-%d-%s", request.GroupID, request.SessionTimeout, request.ProtocolType)
 
 	if request.MemberID == "" {
-		// New member - generate ID
-		memberID = h.groupCoordinator.GenerateMemberID(request.GroupInstanceID, "unknown-host")
-		isNewMember = true
+		// New member - check if we already have a member for this client
+		
+		// Look for existing member with same client characteristics
+		var existingMemberID string
+		for existingID, member := range group.Members {
+			if member.ClientID == clientKey {
+				existingMemberID = existingID
+				break
+			}
+		}
+		
+		if existingMemberID != "" {
+			// Reuse existing member ID for this client
+			memberID = existingMemberID
+			isNewMember = false
+			fmt.Printf("DEBUG: JoinGroup reusing existing member ID '%s' for client key '%s'\n", memberID, clientKey)
+		} else {
+			// Generate new deterministic member ID
+			memberID = h.groupCoordinator.GenerateMemberID(clientKey, "consumer")
+			isNewMember = true
+			fmt.Printf("DEBUG: JoinGroup generated new member ID '%s' for client key '%s'\n", memberID, clientKey)
+		}
 	} else {
 		memberID = request.MemberID
 		// Check if member exists
@@ -113,6 +135,8 @@ func (h *Handler) handleJoinGroup(correlationID uint32, apiVersion uint16, reque
 			// Member ID provided but doesn't exist - reject
 			return h.buildJoinGroupErrorResponse(correlationID, ErrorCodeUnknownMemberID), nil
 		}
+		isNewMember = false
+		fmt.Printf("DEBUG: JoinGroup using provided member ID '%s'\n", memberID)
 	}
 
 	// Check group state
@@ -135,7 +159,7 @@ func (h *Handler) handleJoinGroup(correlationID uint32, apiVersion uint16, reque
 	// Create or update member
 	member := &consumer.GroupMember{
 		ID:               memberID,
-		ClientID:         request.GroupInstanceID,
+		ClientID:         clientKey, // Use deterministic client key for member identification
 		ClientHost:       "unknown", // TODO: extract from connection - needed for consumer group metadata
 		SessionTimeout:   request.SessionTimeout,
 		RebalanceTimeout: request.RebalanceTimeout,