Dynamics simulation analysis has been carried out for transmission mechanism of cross rudder for sightseeing mini-submarine. Based on FLUENT software solution, variation tendency of hydrodynamic coefficients of rudder blade versus different angle of attack has been obtained. High order function fitting of discrete hydrodynamic load versus angle of attack has been implemented on MATLAB. As output curve of fitting function updated constantly by interpolation, it has been taken as input of ADAMS dynamics simulation well. After friction and contact parameters of all kinematic pairs have been set reasonably in ADAMS, dynamics simulation has been worked out. Variation tendency of contact force between tiller and piston rod has been obtained through simulation results. It provides guidance for subsequent optimization design.