The physical property and influential elements of chang2 Formation in the Liuluoyu Block Of Xiasiwan Oil Field were studied by using the cast slices,scanning electron microscope,X-rag diffraction physical property .The research results show that the Chang2 Formation in the Liuluoyu Block belongs to low porosity,and its the most porosity style are porosity among grains and solution hole of feldspar. Sedimentary faces and diagenesis are pivotal influence factors during the evolution stage of reservoir.