Analysis and processing of turn-to-turn short fault of a 390H generator rotor is presented in this paper. The vibration inspection and electrical tests are carried out. According to the results of the inspection and test, the conclusion of rotor turn-to-turn short fault is conducted. Through the disintegration analysis, the fault reason is obtained as deviation of turn-to-turn insulation of rotor. The corresponding treatment of turn-to-turn short fault of generator rotor is also introduced.