The bomber is one type of the important air force. In order to study its electromagnetic stealth performance, the electromagnetic models named with A, B C and D were established respectively based on the US military B-52, B-1B, B-2, and concept aircraft B-3. And their RCS (Radar Cross Section) curves and mean values in different angular domains with different status were calculated by Physical Optics method. The results show that the distribution characteristics of RCS curves are related to the aerodynamic layout and important structural components of bombers. The RCS curves of A, B, C, and D with same state shrink inward in sequence. When the frequency increases, the RCS curve of A changes little and the curve of D towards inside, and the RCS mean values in nose direction of B, C, and D gradually decrease, and the values of C and D in rear angular domain gradually decrease. The pitch angle has a greater influence on the scattering curve oft A, and its peak values in nose and rear direction decrease, and its peak become narrower, the RCS mean values of A are higher, and B, C, and D’s values are smaller which means they possess better stealth performance. In summary, A has poor stealth, B possess better stealth, and C, D have excellent stealth performance.