The Ground Based Augmentation System (GBAS) is called the Local Area Augmentation System (LAAS) by FAA. The LAAS ground facility (LGF) performs the pseudo range carrier smoothing and the integrity monitoring. It produces the pseudo range correction and broadcasts the differential message. The airborne system users can receive GBAS signals to perform pseudo range differential position and approach guidance. This article focuses mainly on the components of GBAS, its working principles, the technological research survey and application prospect. The application of GBAS in the area of civil aviation will achieve considerable direct or indirect economic and social benefits.