As dispersed wind power is close to the load side of the power system, the wind turbines must be able to distinguish the islanding state by themselves. Based on the investigation of the islanding operating characteristics and the sensitivity analysis of the voltage amplitude and frequency change of the point of common coupling (PCC) to the power disturbances of the dispersed wind turbines. A new composite islanding detection method combining positive feedback of reactive power-frequency and passive islanding detection is proposed. A 2.0 MW permanent magnet synchronous generator (PMSG) wind turbine is modeled in MATLAB/Simulink, and the islanding operation and detecting the state of the islanding of PMSG is emulated by simulation. The islanding detection field test is carried out on the 2.0 MW PMSG wind turbine based a controlled RLC load emulator. The simulation and experimental results supported the theoretical analysis and verified the proposed islanding detection strategy.