The Huoxi coalfield is an important coking coal producing area in China. In order to fully identify its coal quality characteristics and coal-forming environment, this paper chooses No. 2 and 9 (9 + 10) coal seams which are representative in southern coalfield to research. By analyzing the data of coal rock, sulfur content, ash content and ash composition of coal samples, the coal quality characteristics were evaluated and the coal forming environment was inferred. The results show that the higher the mirror laziness ratio of coal seam, the deeper the sedimentary environment is covered by water. The higher the sulfur content, the more affected by sea water; The higher the ash content is, the stronger the hydrodynamic force is. The larger the grey component index K is, the stronger the reduction is. The higher the CaO/MgO value is, the wetter the coal-forming climate is. The m value reflects whether the sedimentary environment is fresh or salt water. According to the characteristics of No. 2 and No. 9 (9+10) coal ash with low to medium and low ash composition index and 1 < m < 10, it is inferred that their formation process was influenced by river transport, and they were depositional environments with strong hydrodynamics, reduced form and brackish water. By analyzing other coal quality characteristics of the two coal layers, it is found that there are differences in the coal-forming environment between the two coal layers, as follows: No. 2 coal has the characteristics of low vitreous inert ratio (V/I), low sulfur content and high CaO/MgO value, indicating that the coal-forming environment is a deltaic plain peat swamp environment with low overlying water and humid paleoclimate environment. No. 9 (9+10) coal has the characteristics of moderately high mirror inert ratio (V/I), high sulfur content and high CaO/MgO value, indicating that the coal formation environment is a lagoon peat swamp environment with strong water cover, seawater influence and extremely humid paleoclimate environment.