Abstract: Scramjet inlet flow disturbance was studied for the case when energy impulse was added on the wall of scramjet inlet. The flow is governed by the the 3-D Reynolds averaged Navier-Stokes equations. To split the viscosity flux and the convective flux of the N-S equations, the second order central scheme and the ROE scheme were adopted respectively. With the implicit Gauss-Seidel scheme, the code was advanced in time. The k- turbulence model was used for turbulence simulations. The characteristics of hypersonic flat with energy addition were tested in a hypersonic tunnel by applying a high speed schlieren system. The results show that the numerical pressure contour agrees well with the experimental schlieren photograph. Energy addition could induce strong shock wave interaction which might change the mass flow rate of scramjet inlet sharply. In other words, energy addition can decrease the performance of scramjet inlet flow and inlet unstart might take place at this rate.