The insulation status of generator stator winding is related to the safe and stable operation of generator. When we repair the generator, we need different testing methods to verify the insulation of the different positions of the generator stator winding. In recent years, there is many short-circuit faults because of the insulation defect on the terminal of the stator winding. In generally, when generator need to be repaired, we do the AC/DC withstand voltage test. But when the results of AC/DC withstand voltage test are both OK, the insulation of the stator terminal winding is still not OK. that is the proof that the AC/DC withstand voltage test is not all-powerful. The test of leakage current of terminal stator winding is good effective method to checkout the the insulation of the stator terminal winding. We can find the insulation defect on the terminal of the stator winding with this test and avoid affecting the production even equipment damage.