The invention provides a nuclear fuel assembly repairing, tracking and detecting method. The method is used for tracing detection of a camera for controlling a video detection device in a nuclear fuel replacement assembly, and comprises the following steps: 1, receiving a tracing and monitoring command input from the outside, and setting the shooting area of the camera as a tracking point according to the tracking and monitoring command; 2, acquiring encoder information of a fresh fuel elevator, calculating the height data of the bell mouth of the fresh fuel elevator according to the encoder information, and recording the height data H0 corresponding to the tracking point and the shooting angle theta0 of the camera; 3, calculating the shooting angle theta1 and generating an angle control command according to the height data H0, the shooting angle theta0 and real-time height data H1; 4, controlling the camera to align at the tracking point according to the angle control command; and 5, gathering and displaying the video image in the bell mouth. The camera is controlled to automatically align at the bell mouth without manually adjusting the pitching angle of the camera in the monitoring process, so the method is simple to operate, and the detection safety is high.