The invention discloses a system and technology for carrying out sea water desalination and generating at the same time by utilizing a geothermal resource. The system comprises a sea water taking unit, a raw water pre-treatment unit arranged below sea level, a geothermal heat removing unit as well as a raw water replenishing unit, a reverse osmosis unit, a fresh water lifting unit and a hydraulic generating unit which keep appropriate head fall with the raw water pre-treatment unit, wherein a water diversion pipeline of the hydraulic generating unit is communicated with the sea water taking unit, a tail water pipeline of the hydraulic generating unit is respectively communicated with the raw water replenishing unit and the fresh water lifting unit; the geothermal heat removing unit respectively outputs heat energy to the raw water replenishing unit and the fresh water lifting unit by virtue of a heating pipeline; after sea water is treated by the raw water pre-treatment unit, generating is carried out firstly by virtue of water potential energy, then pressure of tail water after generating is supplemented by the raw water replenishing unit, the sea water is subjected to reverse osmosis desalination, then raw water is separated into fresh water and strong brine, geothermal heat energy-water potential energy-electric energy conversion is realized, and the social problems of scare fresh water and lack of low-carbon generating at present are solved.