Abstract: In order to solve the problems of working condition monitoring of the ocean current machine and the difficulty of long-distance communication and data transmission between the ocean current machine and the shore, the BeiDou Navigation Satellite System (BDS) was chosen to be applied to the ocean current machine's positioning and communication in the sea. The characteristics of ocean currents and several common operating conditions of ocean current machines are analyzed. The positioning principle of ocean current machine based on BDS-RNSS and the short message communication characteristics of BDS are introduced. “Bit Splicing-LZW” double data compression is applied in the short message communication system. A main control system suitable for ocean current machine communication and draft a communication plan between ocean current machine and shore user terminal is designed, aiming to improve communication efficiency and increase data transmission volume.