The vehicle body is an important bearing structure of railway vehicles, which can bear dynamic loads from passengers and bogies. The reliability of the structure is directly related to the service safety of the vehicle.Based on the existing vehicle body standard EN12663, this paper firstly studies the static strength and fatigue strength of the vehicle body, and identifies the static weak position of the vehicle body under standard load.In order to further identify the weak position of the vehicle body under service conditions, a rigid-flexible coupling dynamic model of subway vehicle is established based on the rigid-flexible coupling dynamic theory and finite element method.Using the modal stress recovery method, the dynamic weak positions in various service modes are identified, and the vehicle modes which contribute a lot to each weak position are analyzed.Finally, based on the subway rigid-flexible coupling dynamic model, the dynamic stress characteristic of vehicle body weak position under various service conditions is analyzed, and the service life of key welds of vehicle body structure is predicted based on monte Carlo sampling and Miner linear cumulative damage theory.