There are five types of organic reefs of Changxing stage in East Sichuan:patch reefs on carbonate platform rises and flat

shelf margin reefs and patch reefs in back reef la-goons

and patch reefs near restricted sea.The formation of typical patch reefs was related to the fluctuation of earth crust at the end of the Permian

forming reef core facies

constructed by saccoliths of bound-stones

interchangeably with intermittent shoal facies.Facies-selective dolomitization and dissolution in different stages resulted in the reservoirs of intermittent shoals

reef flanks

etc..The paper deals emphatically with the sedimentology and diagenesis of the reef com-plex.