To solve the problems of high cost of conventional vibration detection technology and difficulty in field installation and implementation in planetary gearbox fault diagnosis of wind power doubly fed induction generator （DFIG）， an indirect diagnosis method directly using DFIG stator current signal is proposed. A simple and feasible fault simulation test bench for DFIG transmission system is established by using general equipment such as motor， planetary gearbox and frequency converter. Through conducting simulation experiments in the laboratory and Hilbert demodulation spectrum diagnosis method， taking planetary gear as an example， the fault induction mechanism of DFIG stator current signatures in transmission system is studied， and the variation law of fault characteristic frequency composition with operating conditions of the generator is investigated. By comparing with the vibration acceleration signal and the torsional vibration signal， it is shown that the DFIG stator current signatures can reflect the vibration characteristics of the radial vibration and the torsional vibration signal of the planetary gear. So， it can be used as an effective alternative or supplementary method for conventional vibration detection technology of actual wind turbine.