Abstract: A numerical study was performed to investigate the effects of thermal excitation using surface discharges in Mach 5 supersonic inlet by solving the unsteady Navier-Stokes equations .Three parameters, including the input power of thermal actuators (E), the number of thermal actuators (N) and the distance between actuator to the first compression corner, were used to study their effects on the control of shock wave and improvement of boundary layer separation. Four cases, which include 1) E =2kW, N =2, S =0.02m; 2) E =3kW, N =2, S =0.02m; 3) E =2kW, N =3, S =0.02m; 4) E =2kW, N =2, S =0m, were considered. From the results for all four cases, it can be observed that the thermal excitation shows significant effect on the control of shock wave and improvement of boundary layer separation induced by shock wave. The heating power of thermal actuator has obvious effect on the control of shock wave. Within the scope of thermal excitation energy considered in this paper, the greater heating power, the greater change of the original shock wave angle, and finally the more obvious change of the separation. The number of thermal actuator N along the spanwise direction affected the energy intensity that input to the air flow. The greater N, the flatter the shock wave surface near the wall. Although the number N did not have significant effect on the spanwise direction pressure distribution of the upper wall, but it had obvious effect on the size of separation on the upper wall. Comparison between cases 1 and 4 showed that the S =0.02m can get a very good control effect, and the S =0m had little effect on the flow structure. This indicated that the thermal actuator must be placed upstream of the control shock with a certain distance.