Abstract: To enhance the system communication capacity, a new design of multi-beam antenna on satellite is presented in this paper. Addressing the issue of uneven distribution of communication capacity demand in irregular service areas, the inconsistency between the capacity and layout is resolved by optimizing the size and location of the feed array. In the optimization course, the feed aperture and location are set as variables, and then the differential evolution algorithm is used to get high gain and C/I performance. In the end, an antenna is optimized and tested to illustrate the efficiency of the method. The measurement results show that the minimum gain in the service area is 40.5 dBi and the minimum C/I is 14.5 dB, which is improved by at least 0.7 dB and 4.4 dB respectively. The method can be used in engineering design to improve antenna design quality and reduce the design period.