Abstract: The thermal stress in magnetron sputtered Al coating on uranium substrate was studied by thermal elastic plastic finite element method (FEM).The thermal stress in Al coating was rather lage and reached the yield strength of Al.A large stress gradient existed at the interface between Al coating and uranium substrate.The end effect resulted in an uneven thermal stress distribution at the free side of specimen,which vanished gradually at the position of about 4 times of the coating thickness from the free side of specimen.The effects of deposition temperature,mechanical properties and coating thickness on thermal stress and plastic strain at the interface were also investigated.The plastic strain at the interface increased with increasing the deposition temperature,but there were small effects of Young’s modulus and Poisson’s ratio on the thermal stress and plastic strain at the interface,and large effects of the yield strength of Al coating on them.Decreasing the thickness of Al coating was helpful to decrease the thermal stress and plastic strain at the interface of Al coating.