Abstract: The approach of dividing the required aperture into several smaller sub apertures is widely adopted in reducing the height of antenna of Satcom onthemove (SOTM). However, the sidelobe of the antenna is deteriorated as a result of the constraint of the size and number of subaperture. The characteristics of the multipleaperture antenna were analyzed in this paper, and some methods for sidelobe suppression were given. In order to reduce the maximum sidelobe level of the antenna ,factors mentioned above are optimized by genetic algorism. Simulation results prove the correctness of the theory and show that using a combination of perturbation of amplitude weighting and reducing the subaperture distance can suppress the sidelobe effectively.