Abstract: As a part of the efforts on distortions analysis of projection welding of car door hinges,a 2D finite element model has been established based on the projection welding of car door hinges.The simulation of whole projection welding processes was performed by a coupled finite element method and the results of projection welding processes,such as the projection collapse mechanism,the nugget formation process and the distribution of temperature after weld,were discussed.Compared with the test results,good conclusions have been achieved.A well base for the on-coming work on prediction of residual stresses and welding distortions was built.