In order to make four steering rudder deflect the same angle at the same time, the RSSR spatial linkage combined mechanism was used. Analytical method was used to establish motion analysis model of mechanism, and the motion relationship curve of input and output of mechanism was solved through MATLAB software. The parametric model of mechanism was built on ADAMS software, and then optimization design was carried out. By calculating sensitivity, the optimal design variables were determined. The results show that the swing angle of the input rod is between the degrees of -11.842 7 and 11.841 9, and the peak is 0.000 8 degrees in difference. The error of steering rudder angle is between the degrees of -0.357 3 and 0.477, and the error within ±0.5 degrees, so optimization of the mechanism meets the design requirements.