Ground-Based Augmentation System (GBAS) is a new generation of satellite navigation landing guidance system developed by the International Civil Aviation Organization (ICAO).By means of ground differential correction, integrity monitoring and other technologies, GBAS improves the accuracy, integrity, continuity and availability of the satellite navigation system, and provides CAT I or higher level precision approach and landing guidance services for aircraft. The system composition and working principle of the GBAS is briefly introduced, and focuses on the analysis of the operation of Tianjin Airport GBAS equipment. It evaluates the operating performance index of the equipment from the aspects of system accuracy, integrity, continuity and availability, which provides a technical basis for the subsequent application of GBAS.