Due to the damage of insulation between blades during operation, a short circuit may occur in the generator, causing local overheating, and even endangering the safe operation of the unit. It is necessary to conduct a loss test on the stator core of the generator. The current test scheme has problems such as difficulty in winding when conducting the large-scale unit tests. A method of using the different frequency current excitation method to test the loss of the stator iron core of the generator is proposed. The finite element simulation model of the iron core with short-circuit defects is established. By comparing the heating conditions of the iron core under the conditions of power frequency large current excitation and different frequency small current excitation, it is demonstrated that different frequency small current can replace the power frequency large current to carry out iron core loss test.