To optimize the thermal environment of gas deflector,the thermal environment influencing factors of avehicle-mounted single-sided deflector are analyzed by numerical calculation,which proves that the height of the deflector, the turning radiusof the deflector and the distance from the deflector backplane to the launch frame are important parameters, having complex nonlinear relationship with the surface temperature of deflector.Based on the comparison of BP surrogate mathematic model and RBF surrogate mathematic model,the RBF surrogate mathematic model with higher determination coefficient and better stability is selected to optimize the deflector. The flow field numerical calculation of optimization results is carried out,which shows that, on the premise of meeting the maneuverability requirements, the optimized max surface temperature of the deflector is reduced by about 400 K, the thermal environment is significantly improved and the diversion effect is better.The optimization error is within 1%, verified the effectiveness and accuracy of the optimization, which provides a reference for the design and optimization of the gas deflector in the future.