Abstract:The short message communication function of Beidou Satellite Navigation System has some limitations in transmission capacity, and there is no receipt information, which is an unreliable communication mode. In order to improve the transmission reliability of long data message, a set of reliable transmission mechanism of long message based on hybrid error correction technology is proposed by improving the transmission protocol. Through the combination of forward error correction and automatic retransmission request technology, it can correct the error in a certain range, and retransmit the transmission error beyond the self correction ability, thus improving the reliability of the transmission.