Abstract: B-spline weld model was established based on the advantages of B-spline fitting nonlinear surface, and the combined heat source model of Gaussian surface and conical body was established based on characteristics of pulse MIG welding base-peak current heat input. The temperature field and stress field of pulsed metal inert-gas (MIG) welded T-joint of A6061 aluminum alloy were simulated by the models, and were verified by the tests. The results show that the relative errors between the molten pool depth and width and the characteristic point peak temperatrue of T-joint by simulation and test results were less than 1.4%, proving the accuracy of the model. The relative errors of the longitudinal residual stress at about 10 mm and 30 mm away from the weld center between the simulation and the test results were 28.0% and 20.6%, respectively, and the calculation accuracy was at least 15.7% higher than that by the simplified weld and double ellipsoid heat source model.