Abstract: The protective suits model on human were established on the basis of the perfect electric conductor and the dimensions of a Chinese male. By means of finite-difference time-domain method, the protective characteristics of the protective suits were studied and the influence of the leakage microwave energy caused by the gap on suits were discussed in detail. The calculation results show that the energy leakage is more likely to happen when the electric field vectors are vertical to the gap. It is found that reduction of whole body average specific absorption rate(WBSAR) in cases of vertical incidence and horizontal incidence is significant when wearing protective suits. The shielding effectiveness(SE) of the protective suits increases with the increase of electromagnetic field frequency (from 300 MHz to 3 GHz), and finally becomes stable. Since the gap is inevitable, special treatment need to be performed to avoid the leakage of energy because SE of the protective suits with gap cannot reach 30 dB.