The VSI and Ethernet Encapsulation Modes Are Configured on the Main Interface, and the mpls l2vpn default vlan is configured on the port.

1.6.1 Configuration Information:
On PE1:
#
Vsi test static
 Pwsignal ldp
  Vsi-id 1
  Peer 111.111.111.111
 Encapsulation ethernet
#
Interface GigabitEthernet2/0/16
 Undo portswitch
 L2 binding vsi test
 Mpls l2vpn default vlan 16
#
On PE2:
#
Vsi test static
 Pwsignal ldp
  Vsi-id 1
  Peer 90.90.90.90
 Encapsulation ethernet
#
Interface GigabitEthernet4/0/16
 Undo portswitch
 L2 binding vsi test
 Mpls l2vpn default vlan 18
#
1.6.2 Packets into the Tunnel:
The packet sent by CE1 is a packet without a VLAN:
 
After receiving the packet, PE1 does not encapsulate the default VLAN configured in the port into the packet. After encapsulating the MPLS label and other information, PE1 forwards it to PE2:
 
If packets sent by CE1 carry one or two layers of VLANs, PE1 strips one VLAN after receiving the packets.
1.6.3 packets out of the tunnel:
After PE2 receives the packet from PE1, PE2 strips off the MPLS label and restores it to the original packet sent by CE and forwards it to CE2:
 
1.6.4 Supplementary Explanation:
The same is true for each version.

The summary of  Handling of VLANs in Packets in Various Versions of L2VPN Configurations .http://forum.huawei.com/enterprise/en/forum.php?mod=viewthread&tid=453137