In engineering practice， the parameters of the electric vehicle mounting system inevitably have certain uncertainties and correlations. Firstly， a polygonal convex set model based on principal component analysis is introduced to effectively deal with the complex situation where the uncertain parameters of the system are correlated and independent at the same time； then， an uncertainty analysis method for the inherent characteristics of the mounting system is proposed in combination with the Monte Carlo method， and the specific analysis steps of the method are given； finally， the method is applied to the analysis of the mounting system of an electric passenger car to verify the effectiveness of the method. The results of numerical analysis show that the response range of the inherent characteristics of the system obtained by the proposed method is more reasonable than that of the interval method without considering the parameter correlation； compared with the analysis method based on the multidimensional parallel hexahedron model， the proposed method can more effectively deal with the case of irregular boundary distribution of the uncertain parameter samples of the system； for the studied model， the correlation of the stiffness parameters of the right and front mounting points has a greater influence on the inherent characteristics， which should be paid attention to in the design research process.