Abstract: Based on the dual-mode working pattern of BeiDou satellites, a position and communication system is designed to transmit the geographic location of full ocean depth marine equipment to the mother ship or control center. This paper adopts the radio navigation satellite system (RNSS) model for positioning and the radio determination satellite service (RDSS) model for sending the location or the transmission information to the receiver’s module. Such system uses photosensitive, angle and temperature sensors combination redundancy working mode to achieve all-weather effective detection for marine equipment operating environment, and then controls the sleep and wake modes of the Beidou module, and the switch between RDSS or RNSS mode by single-chip microcomputer. The experiment results of both location test and sea trials in the Mariana trench show that the system proposed in this paper not only has a high success rate of rapid positioning, but also can effectively save power supply and realize the transmission of short-message communicating.