The researches of robot-fishes based on biological prototype have gained great success.However,they are far behind the fish in nature on the performance of the cruising speed,swimming efficiency and mobility.In this paper,a multi-media motion capture system for live fish was developed to catch the three-dimensional information on fishs swimming motion which would provide data for the research of higher speed robot fish.In this system,eight cameras were fixed on the tank,then intrinsic parameters,cameras position and posture could be obtained with calibration algorithm.