GPS地基增强系统主要用于增强卫星导航系统信息的完好性和提高导航精度，为飞机的精密进近和着陆导航提供服务。介绍了GPS地基增强系统组成结构、服务类型和主要服务信息种类，进而对信息完好性进行了简单说明。然后对GPS地基增强系统的误差源进行了简单描述，根据误差源模型建立地基增强系统的完好性数学模型。最后以A320飞机为飞行平台，通过仿真飞机在着陆过程中的水平保护级和垂直保护级，评估地基增强系统的性能。通过仿真分析，GPS地基增强系统能够满足CAT Ⅲ 的精密进近和着陆导航要求。

GPS Ground Based Augmentation System (GBAS) is an important augmentation system mainly used to augment the navigation information integrity and to improve navigation accuracywhich can also provide approach service and landing service.Firstthe GBAS architectureservice types and main message types are introducedand the concept of integrity is given.Thenthe error sources are described brieflyand an GBAS integrity model is built up based on the error source models.At lastthe GBAS performance is assessed using the GBAS integrity model.The protection level and alert limit are calculated using Matlab software and A320 platform.The simulation results show that the GBAS can provide CAT Ⅲ B service for precision approach and landing.