Numerical simulations of hypersonic rarefied gas flows are important for the aerodynamic design of re-entry vehicles. An investigation numerically of the effect of the wall temperature on the separation flow and the surface quantities of hypersonic gas flow past a large angle compression ramp. The numerical solutions are carried out using the Quasi-Gas Dynamic (QGD) model, which includes the nonequilibrium boundary conditions. Three wall temperatures of 300K, 500K, and 800K are adopted to conduct the numerical investigations. The gas flow is Mach number 6, and nitrogen is the working fluid. The slip velocity and surface gas temperature of the QGD and DSMC solutions give a good agreement. The simulation results show the wall temperature is less sensitive to the slip velocities and significantly affects the surface pressures and gas temperatures. Increasing the wall temperature decreases the recirculation zone size due to the ramp’s large angle.