According to the core observation, a large number of logging and relevant test material analysis, the sedimentary facies were determined to be the front-delta deposition. Four microfacies types were recognized including subaqueous distributary channel, sidewing of distributary ehannel, mouth-bar, subaqueous interdistributary embayment, analyzed the various characteristics of sedimentary microfacies. Research shows that the subaqueous distributary channel is the primarily microfacie of the Chang 61 reservoir and the distributary channel deposits is the main reservoir sands. The evolution and the distribution of the microfacies and sand body exhibition in every number have been studied.