Based on data of outcrop, drilling core, logging, thin section and other macro and micro data, the characteristics of sedimentary facies, reservoir types, reservoir-controlling factors and reservoir distribution patterns of the Perimian Maokou Formation are systematically studied in Sichuan Basin. The author obtains the understanding as follows: (1) The sedimentary pattern of Maokou Formation is influenced by the NW-SE faults formed by Emei taphrogenesis, but not by Caledonian paleo-uplift. (2) Carbonate ramp, slope and basin are three main facies in Maokou Formation. The high-energy shoal of high-stand system tract developed in shallow ramp in the middle-late period of Maokou is the most favorable reservoir sedimentary facies. (3) Two types of reservoir such as hole-pore dolomite reservoir and karst fractured-vuggy limestone reservoir are developed in Maokou Formation. The high-energy bioclastic shoal is the material basis for reservoirs of Maokou Formation. Early dolomization is the key factor for the preserving of dolomite reservoir, tectonic movement and paleo-karstification are important conditions of reservoir development. (4) Dolomite reservoir is mainly distributed in the Ya'an-Leshan and the Yanting-Guang'an areas. Karst fractured-vuggy limestone reservoirs are distributed in the whole basin, but the Luzhou-Kaijiang uplift is the most developed area.