Abstract: The finite element model of the three-points welding processes for the condition compressor upper flange and its case was developed.The ANSYS software was applied.The temperature distributions of the three structures such as pierced,non-pierced and composite were simulated.Based on the temperature results,the relevant welding deformation were simulated by indirect coupling method.These deformations for the upper flange with different structures were compared and analyzed.The model was validated by the experimental welding results.Both the simulation and experimental results showed that the welding deformation of pierced upper flange was maximum.The deformation of the non-pierced was lower than that of the composite.Hence,the non-pierced upper flange was beneficial to decrease the welding deformation of condition compressor.