Electromagnetic stealth has an important impact on survivability of aircraft. According to different missions, the aircraft layouts need to be changed correspondingly. In order to study the influence of layout on electromagnetic scattering characteristics for aircraft, four kinds of typical layouts and electromagnetic models of aircrafts were established. And based on Physical Optics method, the RCS curves of different layout aircrafts were simulated numerically, and the distribution characteristics of RCS were also analyzed. Besides, the frequency response characteristics of electromagnetic scattering were studied for conventional and special layout aircraft models. The results show that the aircraft layout determines the distribution of RCS. In the angular domain of nose direction, the electromagnetic stealth performance of layouts A-1, A-2, B, C and D tended to increase oscillatorily, and RCS mean value dropped from 7.7700dBsm to -30.0673dBsm, the RCS mean value of layout B is -10.4347dBsm. While the electromagnetic stealth performance of rearward and circumferential direction of different layouts increase in turn. The RCS mean values in rearward direction are reduced from 22.7025dBsm of conventional layout to -25.0938dBsm, and RCS mean values in circumferential direction are reduced from 7.0391dBsm to -15.1373dBsm. In high frequency region, the increase of frequency has small effect on distribution of RCS curves, but oscillation of curves is more obvious, and RCS arithmetic mean decreases with the change of frequency.