Abstract: In the process of autobody assembly, the gap between the sheet metal parts introduced by the variations of stamping, location or fixturing is inevitable. As the most widely used joining style, spot welding makes the variation stack up. According to the characteristics of the autobody assembly, the 1/2 axisymmetric model is proposed and the finite element method is applied to analyze the contacting problem and assembly deformation under the squeezing fo rce and electrothermal process.The contact distributions among electrodes and parts and the transient thermal analysis are fulfilled counting for the effects of the gap.The conclusion is provided for the simplification of the autobody assembly variation analysis.