Fluent software was employed to analyze the influence of the k-ω SST turbulence model coefficient on the simulation accuracy of the static pressure at the outlet of the exhaust diffuser of the high altitude platform, in order to accurately simulate the turbulent non-equilibrium flow. The model coefficient was then optimized using a response surface test. The results indicate: With the increase of α1, the simulation accuracy initially increased and then decreased, stabilizing at 0.341. The gradual increase of β* brought the simulation value closer to the target value, thereby improving accuracy. When the simulation value exceeded the target value, accuracy first decreased and then increased; conversely, when the simulated value was less than the target value, accuracy decreased sharply. The increase of β2 also gradually closed the gap between the simulation value and the target value, thereby improving accuracy. Furthermore, the increase of σω2 rapidly brought the simulation value close to the target value and improved accuracy. However, when the simulation value was less than the target value, accuracy decreased slowly.Furthermore, the optimal ranges for the model coefficients α1, β*, β2, and σω2 were found to be 0.2973 to 0.325, 0.056 to 0.098, 0.0756 to 0.089, and 0.69 to 1.1984, respectively. Based on this, a significant sensitivity analysis through response surface experiments revealed that the order of sensitivity was α1 > β2 > β* > σω2. The interaction effects of β* with α1, α1 with σω2, and β2 with β* were found to be significant. The best combination of model coefficients α1, β*, β2, and σω2 was determined to be 0.3052, 0.0611, 0.0826, and 0.853.The best combination of model coefficients effectively im-proves the accuracy of simulation calculations, as demonstrated by the validation of experimental rationality.