Abstract: Based on coal quality and previous drilling data, this paper finds that the grizzle of No.9 coal seam is mainly distributed in the southern part of Yunquan mining area, and the grizzle of No.15 coal seam is mainly distributed in the southeast and north of the mining area. The ash composition index K of Yunquan mining area is positively correlated with the sulfur content of pyrite through the correlation analysis, which promotes the formation of pyrite sulfur; the content of Fe₂O₃ in the coal ash composition is positively correlated with the content of total sulfur and iron sulfide sulfur. Through coal facies analysis, it is found that Yunquan mining area has experienced frequent sea transgressions and retreats during the formation process, and the content and form of sulfur in coal are greatly affected by seawater.