In order to study the effect of sudden changes in wind speed on the electromagnetic force of the rotor of the permanent magnet wind generator, especially in the case of a certain rotor eccentricity, the magnetic field of the air gap is calculated and analyzed by using the mathematical expression and simulation. The two-dimensional model of permanent magnet wind generator is established by ANSOFT MAXWELL software, and the electromagnetic force caused by the current variation and its effect on the main shaft are analyzed. The simulation results show the change of winding current caused by the wind speed change affects the air gap magnetic flux density of permanent magnet wind turbine generator. The rotor eccentricity produces magnetic force along the direction of eccentricity, when the wind speed abrupt change the unbalanced magnetic pull of the rotor is larger than the normal speed.