The three-dimensional (3-D) finite element model (FEM) based on a solid cutter for milling of Aluminum alloy thinwalled workpiece was established based on the theoretical analysis for the thermodynamics and heat transfer process in the metal cutting. The effect on temperature by milling parameters was analyzed by changing the process parameters, such as the cutting depth, the feed speed and the cutting speed. The simulation result shows that the axial cutting depth affected the temperature in milling is the largest, and the effect of feed speed and the cutting speed on milling temperature is smaller. By analyzed with comparison the results from simulation and experiment, the temperature of the simulation is slightly higher than that of the experiment result, but the overall trend of the change and rules are basically coincided well.