With the development of the stealth technique, reducing RCS of antenna has become an important topic. At present, the alteration of antenna's gain and bandwidth has been the main criterion which is used to weigh the means of RCS reduction. Radar Cross Section (RCS) of microstrip patch antennas is analyzed and calculated in this dissertation. Various ways for microstrip antenna RCS reduction are discussed. When antenna RCS is reduced, its radiation performance should be maintained by all means.Firstly, the method of cutting slots on microstrip antenna patch and ground plane for RCS reduction is simulated, and low-RCS microstrip antennas are designed. Secondly, fractal is used to reduce RCS of microstrip antenna. Compact fractal structure has the special ability to reduce the antenna RCS. It is verified by the simulation results that microstrip antenna RCS is efficiently reduced with fractal. Finally, the RCS reduction of aperture coupled array antenna is researched, and low-RCS microstrip array antennas by fractal technology are designed.