Abstract: Rudder shaft gaps of hypersonic vehicles affect the flow structure and corresponding aerodynamic heating characteristics, resulting in local peak heating near the rudder shaft, which poses a safety risk to the local thermal protection system. Numerical simulation of aerothermal environment was carried out for hypersonic plate/rudder, and the influence of gap height, declination angle, Mach number and flight altitude was analyzed. The results show that the peak heating on the surface of rudder shaft increases first and then decreases with the increase of gap height. It also increases with the increase of declination angle and Mach number, and decreases with the increase of flight altitude. For the calculation state and calculation model in this paper, the peak surface heat flux reaches the maximum value when the gap height of the rudder shaft is about 8 mm. When the rudder declination angle is 35°, the peak heat flow is about 3 times more than that of the rudder declination angle of 0°. For incoming flow heights of more than 40 km, the peak value of surface heat flow has been reduced to a minimum.