The effectiveness of shale reservoir and pore types and growth level have a close relationship. Using electron microscope, thin section , mercury injection data and studying the pore types and controlling factors in shale reservoir of E_s3 formation in south slope of Dongying Sag. The result revealed that the clay intracrystalline pore, pyrite-recrystal pore, micro fractures and dissolved pore in the layer developed well, and the effects to developing of one pore types differs to another. Then combining the cyclic and sequence on vertical and analyzing the development rules of pore in shale, the result show that clay intracrystalline pore and pyrite-recrystal pore in E_s3 formation developed well, strawberry pyrite-recrystal pore just develop in SQ1, and with the rise of lake level, its scale have a phenomenon of tendency to periodic decrease. Micro fractures and dissolved pore as the effectiveSstorageSspaces, the former usually developed in lowSsystemStract (LST), while the latter developed in deep layers and mainly in lacustrineStransgressive system tracts (LTST) and LST in SQ2. The law provide the terms for finding favorable shale reservoir in well profile.