Abstract: A constant life fatigue limit model,which describes typical glass fiber reinforced plastics（GRP）,was proposed and compared with three classical models to effectively evaluate fatigue life of wind turbine blades under random loads. It also pointed out that GRP had different damage accumulation modes in the tensile stage and the compression stage,reflecting that the constant life fatigue limit curve is not symmetric,but looks like a clock. The prediction effect of the proposed model in the stress-life data was compared and analyzed. In additon,ANSYS software was used to establish a numerical simulation model of wind turbine blade. The random variation characteristics of the mean stress and stress amplitude under random load were analyzed. Apart from that,the experimental data were used to fit the quantitative damages of the stress-life curve of the wind turbine blade composite. Finally,through the Miner linear fatigue damage accumulation method,damages in all cycles were accumulated to calculate the total fatigue life. Based on the simulation data,results verified the reasonability of the proposed model in predicting fatigue life of wind turbine blade.