The sedimentary facies in Wen'an slope of Baxian depression have been redefined as delta and lacustrine facies. Upper Es1 is dominated by delta front sedimentation with distributary channels and river mouth bars. Lower Es1 shows shallow lake sedimentation with gravity flow subfacies and carbonate platform subfacies. This new understanding helps in recognizing diagenesis and sedimentary evolution, and provides a basis for predicting oil and gas exploration zones.