It is significant to study the structure safety of thinwalled vessel under thermo-solid coupled load. In allusion to a thin-walled vessel of failure receiving low-frequency and high-temperature thermal shock and pressure load, direct coupling model, temperaturerelated material model and Finite Element Method(FEM) were applied to calculate the response of transient temperature field and transient stress field, based on which the influence of temperature load on failure of the vessel was analyzed. It shows that the node temperature response of the vessel cross-section has obvious thermal-shock characteristics that high temperature of inner wall and large gradient of transient temperature appear; transient peak thermal stress caused by thermal shock is obviously higher than that caused by internal pressure, and the periodic coupled stress plays an important role in the formation of cracks distributing around the placket of the vessel.