The acquisition, pointing and tracking (APT) system of laser wireless energy transfer for unmanned aerial vehicles (UAV) is the guarantee of stable energy at the receiving end of the system. In order to solve the problem of high efficiency and reliability of charging link in energy transmission process, considering the characteristics and practical requirements of UAV laser energy transmission system, an adaptive region of interest was established in the design for improving image processing speed, reducing noise and accurately extracting target coordinates. Considering multiple errors, Kalman prediction algorithm was used to achieve stable tracking. According to the characteristics of the system, the calculation scheme of power transmission efficiency of the system was put forward. The results show that, when the flight speed of UAV is within 18km/h, APT system can track the UAV accurately from 300m to 500m. The tracking accuracy is within 320μrad. The scheme can ensure the tracking accuracy and reliability of laser energy transmission process.