Abstract: A design method of marine gravity system based on inertial platform gravity measurement and multi-source information is proposed in this paper. This method is based on the inertial platform, which combines navigation information, inertial information, sounding (diving) information, and adopts precision temperature control, high precision gravity measurement and error compensation, underwater autonomous gravity measurement, etc. It can achieve the stability of high precision gravity measurement with long-endurance in the surface of the water or underwater conditions. The experimental results show that the marine gravity system designed in this paper can achieve the repeatability precision of 0.41 mGal(water) in the typical application scenario, 0.56 mGal (underwater), dynamic closure of 1.87 mGal, and has good engineering application value.