In order to take the rotating effect into consideration and predict the fatigue life of wind turbine system exactly,a fatigue life prediction model based on the rotationally sampled spectrum is proposed in this paper.Firstly,the rotationally sampled spectrum taking the rotating effect into consideration is deduced through the Fourier transformation and compared with the Von Karman spectrum(fixed point spectrum).Based on the rotationally sampled spectrum,a fatigue life prediction model which derives from the Palmgren-Miner(P-M) linear damage model is provided.Then the fatigue life analysis of a 1.25 MW wind turbine system is carried out.The results show that the energy of the rotationally sampled spectrum transforms significantly from the low frequency region to the high frequency region.Besides,multi-peaks also appear in the high frequency region because of the energy shift.The fatigue life prediction model based on the rotationally sampled spectrum can predict the fatigue life and evaluate the security of the wind turbine structure more exactly compared with the one based on the Von Karman spectrum,which will overestimate the fatigue life and is unsafe for the fatigue life prediction of wind turbines.