Abstract: Based on study of sedimentary setting and structural feature of Lianglitage formation, integrated with analyses of drilling, core, well logging and geochemical data, the sedimentation of Lianglitage No.3to No.2members of the Upper Ordovician is dominated by continually vertical accumulation during highstand system track, which is the main development period of reef?flat complex. The vertical zonality of denudation and cementation in the reef?flat complex is obvious under control of the multi?phase reef?flat complex constructions and eustatic secondary cycles, and the secondary pore spaces mainly develop in the atmospheric vadose zone and upper phreatic zone, while cementation occurs in the bottom of phreatic zone. Atmospheric diagenetic lens formed by selective denudation are mainly distributed in the middle?upper parts of the individual phase of reef?flat sedimentary cycles, which becomes the effective storage and seepage spaces composed of intragranular solution pore, moldic pore, intergranular solution pore, and intermittently distributed along the high energy facies belts of the rimmed platform. The syngenetic paleokarst feature, the reservoir control mechanism and dev