///Research on oolitic beach reservoir of Feixianguan Formation in northern Sichuan Province, with a combination of macro and micro methods, shows that the main reservoir rocks are oolitic dolomite and oolitic limestone, reservoir space is dominated by secondary pores and the reservoir property is relatively poor appearing as fracture-pore type and pore-fracture type with low porosity and low permeability. Reservoir of Feixianguan Formation in the study area was formed by eustatic sea level fall. Development and evolutions of the reservoir were controlled by deposition and diagenesis. The generation of ancient highland of Permian Changxing reef and Longmenshan island chain provided Feixianguan Formation with high energy sedimentary condition.