The efficiency of numerical simulation for thermochemical non-equilibrium flow of hypersonic vehicles has always been one of the pain points in engineering applications. Based on the time-consuming analysis of thermochemical non-equilibrium flow simulation, an adaptive relaxation coupling simulation method of thermochemical non-equilibrium flow was established by capturing and judging the flow field characteristics or iterative characteristics. The accuracy and efficiency of the adaptive relaxation coupling simulation method were tested and analyzed under different parameters, different physical and chemical models, as well as different thermochemical non-equilibrium flow characteristics. The results show that, the calculation time-consuming ratio of non-equilibrium source term and its Jacobian matrices processing, multi-component gas energy function and transport coefficient could reach 62.04% under the current conditions. The adaptive relaxation coupling simulation method established based on time-consumption analysis can significantly enhance computational efficiency, reducing computational time by up to 45.70%. The proposed method does not reduce the convergence and accuracy of numerical iteration, and has the same calculation fidelity and accuracy as the coupling simulation method of full physical models. It can be easily implemented on various static or dynamic software architectures without changing the computational domain dynamically and adjusting the logical structure or computational flow greatly. This method is more effective in fine physical and chemical model, and can partly solve the difficulty of balancing computational accuracy and efficiency of complex engineering problems.