According to the requirement of underwater welding robot used in the fuel pool of the nuclear power station, a set of binocular stereo vision system was designed. The compositions of the system, and the connection and cooperation of the compositions to complete the image acquisition work were introduced. Based on the requirement of actual work, underwater camera and light source were designed. The type choice, the structure and the seal methods of camera and light source were also introduced. The holder to install and fix the camera and light source was designed, which can swing around and realize the pitching motion. The practical application proves that this system is stable, easy to operate, and responses fast, which can obtain clear underwater realtime images.