The invention discloses an overwater-underwater dual-purpose portable search-and-rescue position indicating beacon and a position indicating method. The overwater-underwater dual-purpose portable search-and-rescue position indicating mark comprises a positioning device, a microcontroller, an AIS transmitting device and an underwater acoustic transduction device, wherein the positioning device is connected with the microcontroller, and used for acquiring current location information and sending the current location information to the microcontroller; the microcontroller receives the location information sent by the positioning device and sends the location information to the AIS transmitting device; the AIS transmitting device is connected with the microcontroller, receives the location information sent by the microcontroller and transmits the location information outward according to a set time interval; and the underwater acoustic transduction device is used for generating acoustic signals. Application of th
