Abstract: In order to explore the effect of ambient temperature on blade stiffness detection and degradation rate,the 65 kW wind turbine blade is taken as the research object. By the fatigue test under different temperatures,the stiffness degradation curve is obtained,which shows that the temperature influence on the stiffness of each blade section is slightly different but very close. By the comparative analysis of the stiffness degradation among constant temperature,normal temperature and wind farm temperature,it is found that if the temperature effect is considered,the stiffness degradation analysis of blades should be more accurate.