Based on the comprehensive analysis of drill core, petrology and sedimentary facies features of well log in Wannian Mine, the sedimentary environment of coal-bearing series in the mine was analyzed and studied. The result showed that barrier-lagoon and wadden- lagoon- carbonate sedimentary system was developed in Taiyuan series sedimentary period, including sedimentary facies types like carbonate platform, wadden, lagoon and barrier bars, etc.. The land and sea transitional facies was main facies during Shanxi series period, deltaic depositional system was developed, mainly with front delta, lower delta plain, upper delta plain and other sedimentary facies types. Sedimentary period from Taiyuan series to Shanxi series reflected the gradually reduced sea level, sedimentary environment changed from marine-continental transitional facies to continental facies, the intensity of coal accumulating ranged from good - bad - good - bad.