This study proposes and designs an automatic defect detection system based on UAV images for wind turbine blades, aimed at alleviating problems with manual detection methods, such as low efficiency and inaccurate defect detection. This paper introduces the system's image acquisition system, acquisition method, defect detection principle, and detection result. This system uses a UAV as the flying carrier to realize automatic inspection of wind turbine blades, thereby improving the inspection efficiency and reducing the manual workload. Through image segmentation and defect detection algorithm design, automatic detection of suspicious defect areas is achieved. Double light fusion of visible and infrared light improves the accuracy of automatic blade defect recognition. After multiple field tests and verification, the system is shown to accurately and quickly realize the automatic identification and detection of defects, such as bulges, cracks, and wrinkles.