Because of the high radiation and complex structure in the nuclear power plant, the operating personnel can be affected by radiations that greatly threaten their physical security and life safety. The reactor multifunction robot for object salvaging underwater is designed to solve this problem. Firstly, the manipulator is modeled with the DH rule, and its forward kinematics formulation, inverse kinematics formulation and singularities of the manipulator are calculated. Considering the comprehensive influence caused by factors such as the water resistance, additional mass force and buoyancy force, dynamic equations of the underwater robot are established, which can describe the complicated dynamic behavior. Finally, an engineering prototype of the third generation of reactor robot is developed. The results of the grabbing test show that the engineering prototype of the reactor multifunction robot for object salvaging underwater realizes the goal of grabbing foreign matters in the nuclear reactor pool.