A scheme is proposed for the quad-rotor UAV to implement autonomous tracking with an airborne camera. The machine vision module OpenMV is used to acquire the ground image, and the image is divided into five regions. By calculating and analyzing the black lines in each region, various track elements are identified to obtain the horizontal deviation of the UAV relative to the path and the angle between the UAV and the path.The position outer loop is designed by the Linear Active Disturbance Rejection Controller (LADRC), and the speed inner loop adopts a PID controller, and the two loops form a position-speed cascade control to eliminate the horizontal error. The bang-bang control algorithm is then used to correct the aircraft heading. Experiments were carried out to track the 8-shaped trajectory. The results show that the scheme has a good path recognition effect and can make the quad-rotor UAV accurately and stably track the ground black guide line.