Satellite-to-ground laser communication utilizing quantum encryption has emerged as a novel method for long-distance information transmission， offering higher bandwidth and enhanced data security compared to traditional RF systems. This approach is characterized by its high bit rate， miniaturization， and low power consumption. To establish a reliable laser communication link between satellites and ground terminals， precise tracking and alignment between the ground optical terminal and the satellite optical payload must be maintained within the designated time window. This requirement is particularly challenging as the ground optical terminal operates under complex environmental conditions and various disturbances. Therefore， the design of a lightweight， high-precision ground laser tracking terminal， coupled with a stable and reliable tracking control algorithm， is essential.In this study， we propose a composite-axis tracking system incorporating dual detectors. The optical terminal is designed with a lightweight structure， utilizing a large-aperture reflective imaging system with an integrated， compact architecture and lightweight materials， achieving a weight reduction of over 50% compared to traditional designs. A two-stage tracking control system is implemented， combining a gimbal and a fast steering mirror. The control system integrates parameter identification and auto-tuning optimization using a PCA-NN intelligent algorithm， reducing the PV （peak-to-valley） tracking error within the time window from over 20″ to less than 5″. This approach effectively addresses the challenges associated with lightweight laser communication tracking systems， providing a robust platform for broader applications in interstellar laser communication technologies and meeting the stringent requirements of quantum-encrypted laser communication.