Abstract: The studied samples are collected from the depth of 111.68 m in the eighth member of the Shihezi Formation to the second member of the Shanxi Formation through the Su10-28-33 well in the Sulige Gas Field,Ih Ju Meng,Nei Mongol.The analysis of more than 1800 pieces of samples,in integration with the examination of sedimentary environments,shows that the sandstone reservoirs were deposited in the transitional environments from the braided stream to the meandering stream in the second member of the Shanxi Formation,whereas those from the eighth member of the Shihezi Formation are assigned to the typical braided stream deposits.Two major fluvial depositional cycles are developed in the exploration intervals at the boundary between the eighth member of the Shihezi Formation and the first and second members of the Shanxi Formation.Lithologically,the sandstones with good physical properties have the features of coarser grain sizes,low mud contents,and low contents of lime(dolomitic) cements.