Abstract: The metro gearbox is subjected to impact loads during operation, which affects the reliability and service life of the gearbox. To study the impact of impact loads on the gearbox, this paper established a three-dimensional model of the gearbox and conducted finite element stress analysis through SolidWorks. The response surface method was used to screen out the dimensions that have a greater impact on stress, and the CCD experimental design method was adopted for sample calculation. The corresponding response surface model was fitted through non-parametric regression. Combined with the Monte Carlo method, the probability density function of the equivalent stress under the extreme and short-circuit conditions was obtained by sampling the response surface. The static reliability of the box was obtained using the stress-strength interference theory, and the dynamic reliability of the box was further obtained by using the order statistics theory.