The characteristics of temperature distribution of an automobile alternator with torsional blades are analyzed in this paper. Firstly, the experimental test rig and the numerical model are established. The consistency between experiment data and simulation results is verified. Then, the effects of the torsion angles on temperature characteristics are explored and their mechanisms are revealed through fluid flow and heat dissipation analysis. The results show that the twisting of the rear fan blades can improve the heat dissipation performance, and when the torsion angle is positive the heat dissipation performance of the alternator is greatly improved with an increasing mass flow rates.