Abstract: In this study, the main freight locomotive in China is taken as the research object. Based on the topological analysis of this type of locomotive, according to the actual structure of the product, the mechanical parameters such as the primary axle box spring, the secondary rubber pile and the transverse oil pressure shock absorber are mainly considered, and the multi-body dynamics modeling is carried out. According to the relevant standards, several working conditions are determined, and the dynamic performance of this type of heavy-duty electric locomotive is evaluated. The Sperling method is used to analyze the stability of the locomotive, as well as the nonlinear critical speed of the locomotive, derailment coefficient, wheel load reduction rate, wheel-rail lateral force stability and safety analysis. The results show that under the condition of curve, the curve radius has little effect on the safety of locomotive. In the speed range of 50-70km / h, the running speed of the locomotive is closely related to the running stability of the locomotive. The research has certain guiding significance for the design of domestic locomotive products.