Based on the field data of the wind farm, the main components that affected the reliability of the wind turbine were determined according to the failure rate, failure time and maintenance cost. The specific reasons for the failures of the main components were analyzed by using the FTA method; the correlation analysis method was used to analyze the correlation between wind turbine failure rate and environmental factors,such as wind speed, temperature and environmental humidity; the seasonal characteristics of wind turbine failure rate were analyzed by using seasonal index.The results show that the faults of hydraulic system, electrical control system and yaw system are the main reasons for the high failure rate of wind turbine, which accounts for 67.91%; although generators and transmission systems have lower failure rates, they have higher average failure time and maintenance costs; the failure rate has obvious correlation with wind speed, temperature and humidity, among them, there is a negative correlation between the failure rate and wind speed, and a positive correlation between the failure rate and temperature & environmental humidity.