Abstract: wuershen depression, a fault-subsided basin formed on the premesozoic fold basement, is about 2350km². Deltaic deposit, mainly developed in the middle and upper parts of Da moguai he group, could be dividede into two kinds: river dominated del la and wave dominated delta. We studied the depositional characteristics of delta reservoir from the shapes of sandbodies, sedimentary succession, component, structure and size distribution. The delta reservoir underwent a complicated diagenetic history. The compaction resulted in a decrease in original porosity. The authigenic cements filled the intergranular space. The dissolution made secondary porosity. The reservoir properties were the function of diagenetic strength. According to the major diagenetic events or diagenetic facies which affected the reservoir proporties the deltaic sandbodies were divided into three kinds of reservoir: (1) carbonate cemention type, (2) compaction-filling type, (3) unsteady elastics dissolution type. The reservoir characteristics of deltaic sandbodies were controlled by both the microfacies and di a genesis of the sandbodies.