Keywords: 
• Junggar basin

Abstract: Based on a large number of thinsections, casting thinsections and scanning electron photomicrographs observation , the characteristics of Triassic dissolution in KeBai area, northwestern margin of Junggar Basin are systematically studied. Triassic dissolution is generally developed in KeBai area, with abundant typical phenomena, and reservoir is obviously reformed , so dissolution is the most important type of diagenesis in the study area. The lithology characteristics of "low compositional maturity, lowermiddle textural maturity " provide a sedimentary basis for diagenesis. The dissolution of feldspar is the most common in the area, and cementation is weak, with little calcite and analcime dissolution, quartz is slightly dissolved under alkaline condition. The type of pore space and the vertical evolution of porosity on different walls of the fault belt are determined by dissolution. The intensity and distribution of dissolution was affected by the rock type, matrix content, microfacies and other factors.