Co-simulation based on ADAMS and MATLAB software is introduced in this paper to study dynamic characters of one kind of water strider robot. Control model, composed of DC servo motor model and hydrodynamic model, is built in MATLAB/Simulink software. Combined with mechanical model built in ADAMS software, electro-mechanical co-simulation model of whole water strider robot system is developed. Simulation results show that co-simulation platform is established successfully. Movements on water surface of water strider robot subjected to water resistance and motor driving force can be viewed clearly. Furthermore the platform can be used to study the influence of parameter variation on robot movement characters to achieve optimized robot.