In establishing model process of three-dimensional heat source model of aluminum alloy friction stir welding,heat flux density range of shoulder,stir pin’s side and bottom generating heat quantity is uncertain,which needs certainty through verification,increases the difficulty and workload of modeling. For this problem,three-dimensional friction stir weld heat source model is established,and uncertain parameters in heat source model are determined. At the same time,effect of these parameters changing for welding temperature is resear-ched in the simulation. In addition,according to the effect law of parameters changing,library of parameters of friction stir welding heat source is established and inference rules are designed. Friction stir welding of aluminum alloy heat source model expert system of fast establishing model are achieved.Finally,temperature field results of friction stir welding experiment have validated expert system function. Expert system significantly reduce difficulty of numerical simulation of friction stir welding,and is beneficial to promote the popularization and application of numerical simulation technology of friction stir welding of aluminum alloy.