In order to solve the problem that blade fixing bolt cannot be detected quickly and conveniently in the field in actual production, this paper proposed a field rapid detection method of wind turbine blade fixing bolt defects based on field programmable gate array (FPGA), and Yolov4-tiny is selected as the basic algorithm. Nonetheless, the original Yolov4-tiny was not suitable for detecting small defects, so this paper improved the Yolov4-tiny to enhance the detection effect. Next, the convolutional operations in the algorithm were encapsulated into intellectual property (IP) cores by high-level synthesis (HLS) and Vivado, and parallel computation was realized using FPGA features. In the end, using Python to call the IP core and the FPGA hardware library, this paper achieved the purpose of rapid detection. Compared with traditional detection methods and other algorithms, the accuracy and speed of this method are significantly improved, which has a good application value.