Abstract: An assessment method of signal coverage is proposed for GBAS(ground-based augmentation system) landing system(GLS) based on BeiDou Navigation Satellite System(BDS). The covering situation is discussed from two aspects: the satellite coverage on earth and the covering of VHF data broadcast (VDB) radio signal. In the first aspect, firstly the grid-point analysis method and visibility function are used to evaluate the cover multiplicity of BDS and other four performance index which are percent coverage, maximum coverage gap, mean coverage gap and time average gap. Then the satellite visibility is analyzed from the user perspective. In the second aspect, the earth curvature and the terrain occlusion are considered into the propagation of electromagnetic wave. In addition, combining with the minimum cover airspace of the VDB signal which is regulated by Federal Aviation Administration, a VDB locating method is proposed based on the proposed assessment method. Experimental results show that the signal coverage of GLS based on BDS and the location of VDB can be determined reasonably by the proposed methods.