Aiming at the severe engineering challenges of navigation signal loss and inaccurate landing precision faced by unmanned aerial vehicles (UAVs) when performing tasks such as equipment inspection and material delivery in typical low-altitude mixed-obstacle scenarios like suburban industrial parks and dense building complexes, a highly reliable remote navigation system for UAV communication terminal autonomous landing has been designed and implemented. Oriented towards practical application, at the hardware level, the system adopts an airborne-ground station cooperative architecture. The communication terminal supporting 4G/5G and dedicated wireless data transmission is installed in separate zones from the GNSS module, with added electromagnetic shielding layers to avoid interference from both physical isolation and electromagnetic protection dimensions. A customized serial port protocol interacts with the STM32H743 microprocessor to temporarily store critical positioning data during communication interruptions, preventing navigation disconnection caused by data loss. The ground data reception center is equipped with an industrial-grade server, same-frequency band wireless data transmission reception modules, and a real-time display terminal to ensure stable data transmission. At the algorithm level, a navigation algorithm integrating PnP positioning and Extended Kalman Filtering, combined with visual positioning and multi-sensor data fusion, enhances landing accuracy and robustness in complex environments. Real-flight experimental results show that this method controls the roll angle, pitch angle, and yaw angle within the ranges of [-1.5°, 0.5°], [-0.5°, 0.5°], and [-2°, 2°], respectively, all demonstrating optimal stability and accuracy, and can effectively resist interference from low-altitude obstacles. Furthermore, this method enables precise control of the UAV attitude, resulting in the final landing point coordinates being consistent with the ideal landing point coordinates at (30m, 4m, 10m), meeting the requirements for precise UAV operations and providing reliable navigation technical support for low-altitude tasks such as substation equipment inspection.