Abstract: A set of multi-lithological coarse-grained sediments dominated by conglomerate are developed in the Lower Triassic Baikouquan formation in Mahu sag, Junggar basin. Researchers conducted in-depth studies on litho-facies types, but some problems still exist in lithofacies classification and relationship between lithofacies and sedimentary microfacies. The reason is that it is difficult to express the lithofacies associations in different microfacies and to differentiate the characteristics and association differences among similar microfacies by means of small amount of lithofacies types. Based on the systematic descriptions of lithology, color, sedimentary structure, sorting, roundness, orientation, fabric support, cementation type, cement composition, the max. grain size, average grain size, oil-bearing property and gravel component from 77 cored wells in Mahu sag, the paper proposes a new lithofacies classification method, which can be used to classify and denominate lithofacies mainly according to 4 properties such as sedimentary structure, color, grain size and fabric support. 227 lithofacies types have been identified from the cores of Baikouquan formation in Mahu sag, including 153 for conglomerate, 58 for sandstone and 16 for mudstone. The results well reflect the diversity of lithofacies of Baikouquan formation in Mahu sag, lay a foundation for accurate description of sedimentary characteristics of different sedimentary microfacies and provide basis for detailed sedimentary facies identification