In order to transmit ethernet packets over E1 link reliably and stably, a high-level data link control(HDLC) frame-forming and frame-de-framing processing circuit based on E1 link is proposed. This circuit adopts HDLC protocol to encapsulate ethernet packets sent by media independent interface(MII) in the sending part of the system and send them through wide area network(WAN) interface. In the receiving part of the system, the data received by WAN interface is unsealed. The simulation results show that the initial ethernet data frames can be recovered successfully at the receiving end when ethernet packets are sent through MII at the sending end.