Currently, with the strengthening of caborate reservoirs exploration in Sichuan basin, strong heterogeneity becomes a practical problem which has seriously hindered the exploration and development of reef and bank gas reservoirs. With the typical reef and bank section of Changxing Formation as the research object, its external features were carefully observed in combination with the analysis of thin sections and rock data, and the authors investigated the reservoir heterogeneity features and formation mechanism of Panlongdong reef and bank profile in Changxing Formation of eastern Sichuan basin. The results show that a strong cyclicity and reservoir heterogeneity can be observed in the vertical direction of Panlongdong reef and bank facies. The reservoir rocks distribution, reservoir thickness, the degree of dolomitization and dissolution phenomenon exhibit cyclic variation with the cyclical change of the sea level. Reef and bank reservoir heterogeneity is controlled by high-energy sedimentary facies, changes of sea level and constructive diagenesis. The high-energy sedimentary facies is the key controlling element of primary pore, which determines the sedimentary heterogeneity. Dolomitization and dissolution are advantageous to the reef reservoir formation. Atmospheric fresh water leaching transformation plays a key role in optimization of the reservoir. Sea-level fluctuation determines the cyclicity of reef and bank development, and selective reform of constructive diagenesis deepens the reservoir heterogeneity.