GBAS can provide a remedy for many shortcomings of traditional navigation systems. To evaluate the navigation performance and system performance of GBAS and to verify the integrated performance of GBAS approach services under different types of operation conditions, it is usually necessary to conduct corresponding flight tests. Considering that GBAS flight tests need to be conducted in combination with specific test equipment and operating environment, the process is always very complicated. Therefore, simulation data is adopted instead of real-collected data to simulate and verify the landing period Category I Precision Approach (CAT I) and Required Navigation Performance (RNP) of GBAS in a laboratory environment with Flight Gear and Matlab software. The simulation results show that GBAS can meet the CAT I approach and landing performance requirements and can provide a solution for the promotion of Beidou-based GBAS technology in the civil aviation field.