Abstract: Attenuation characteristics on high power microwave ( HPM ) with different band penetrating through reinforced-concrete layer were evaluated by experimental research connected with finite difference time domain method. The factors affecting shielding effectiveness such as concrete, reinforcement net, and steel fiber were studied by experiment and simulation of multiform reinforced-concrete models. The results show that various type reinforced-concrete has certain shielding effectiveness to HPM. With thicker concrete, smaller mesh, and more steel fiber, the shielding effectiveness of reinforced-concrete is better. To reduce the size of mesh and add the content of steel fiber, the shielding effectiveness can be increased evidently. However, improving diameter of steel and layers of mesh only affects little for the shielding effectiveness, although these measures are useful. Reinforced-concrete structure should be rationally used to practice electromagnetic protection in the engineering.