Abstract: This paper took the flat plate/air rudder model as the research object, aiming to reduce the aerodynamic heating acting on the thermal-protection ring of the rudder shaft through local shape optimization. Numerical simulation methods were used to calculate the flow field of the flat plate/air rudder model at typical rudder deflection angles. By analyzing the flow field structure, flow characteristics, and heat flux distribution, the aerodynamic heating mechanism of the thermal-protection ring was studied. On this basis, two local shape optimization schemes for the thermal-protection ring were proposed (Scheme 1: adding beveled chamfers to the thermal-protection ring; Scheme 2: lowering the rudder surface height on the basis of Scheme 1) and numerical simulation was carried out to assess their impact on the thermal environment of the thermal-protection ring. Analysis of the flow field structure revealed that shock-boundary layer interaction causing flow separation and reattachment is the main reason for the local high heat flux on the windward side of the thermal-protection ring. The two optimization schemes proposed in this paper can effectively reduce the peak heat flux and the area of high heat flux on the thermal-protection ring. Scheme 2, by lowering the rudder surface, places the thermal-protection ring further into the recirculation zone, resulting in a better cooling effect. In the design of the thermal-protection structure of the air rudder, it is necessary to comprehensively consider the spatial constraints and reasonably design the angle of the beveled chamfer and the sinking distance of the rudder surface, in order to reduce the aerodynamic heating acting on the thermal-protection ring.