Abstract: This paper analyzes the sedimentary structural setting and sedimentary facies symbol of Ziniquanzi formation of the Paleogene in southern margin of Junggar basin, and suggests that the Ziniquanzi formation in this area appears braided river delta deposits, and develops such three subfacies as delta plain, delta front and prodelta as well as eight microfacies like underwater distributary channel and others. The overall displays the evolution characteristics of lake regression and transpression. The contrast of the sedimentary facies, petrophysical property and productivity performance indicates that the most favorable sedimentary microfacies is the underwater distributary channel