The doublyfed induction generator (DFIG) was prone to overheat faults of stator and rotor windings in long term operation. The winding temperature was taken as the object of study. Based on the analysis of the causes of winding overheat fault, tests were carried out from two aspects of motor thermal performance and parameter identification. Using parameter identification method, resistance was identified for the stator and rotor windings based on the electromagnetic mathematical model of motor, and then the temperature was calculated according to the relationship between resistance and temperature to judge whether the windings were overheated. Finally, the correctness of the identification method of stator and rotor winding parameters was verified by MATLAB simulation, which provided theoretical support for the diagnosis of DFIG overheat fault.