The GBAS Approach Service Types and its technology evolution trend is introduced. The key points, international standardization status and application status of GAST C and GAST D GBAS are summarized. The GAST F key technical points of the SESAR DFMC GBAS conceptual framework are introduced in detail. The other solution of DFMC GBAS is analyzed, including algorithm processing flow, fall back modes, messages and data link capacity.