Link parameter autonegotiation method, terminal and system based on hdlc protocol

Disclosed is a link parameter autonegotiation method based on the High Level Data Link Control (HDLC) protocol, which comprises: a slave end sending a SUBME frame to a master end to request to establish a link connection; the slave end receiving a UA frame returned by the master end according to the SUBME frame; and the slave end performing link parameter negotiation with the master end according to the UA frame to establish the link connection with the master end. Further disclosed is a link parameter autonegotiation system and terminal based on the HDLC. By adopting the method, system and terminal, reliability and efficiency of link transmission can be enhanced.