Abstract: The southern edge of Yonglong mining area is a large mining area which has not been fully developed at present, and is located on the edge of Ordos continental coal basin. In order to explore the relationship between coal quality and coal forming environment in large continental basin, starting with the basic data on coal quality, the geochemical data were discussed in detail, and the significance of the indexes such as V/I, ash, sulfur and K value for the coal forming environment was analyzed. The results show that the main coal seam is low rank bituminous coal of "low to medium ash" and "low to extremely low sulfur". The main coal seam is covered with water, and pH has the characteristics of "S" type decline in vertical direction, while Eh is opposite. The third coal group was of small closed lacustrine facies, and the second coal group was of lake flat and river facies. The coal accumulation was controlled by paleotopography, paleoclimate and uneven subsidence.