A large number of dissolution pores were developed in the Sinian Dengying formation dolomite reservoirs in the Sichuan basin due to meteoric karst during the Tongwan tectonic uplift at the end of Sinian. Many pores were found unfilled by diagenetic minerals and well preserved in the deep dolomite reservoirs even though the dolomite reservoirs had experienced long burial diagenetic process. Based on detail petrology and mineralogy characteristics of samples from well and outcrop profiles, the upper part of the Dengying formation dolomite reservoirs with bitumen generally has many pores well preserved. However, the pores in the lower part without bitumen were heavily filled by diagenetic dolomite minerals. According to the Lin 1 well, porosity of the upper part is generally more than 3.0%, up to 10.6% and 4.0% in average; but the lower part is commonly less than 3.0% and 1.95% in average. From edge to central of the dissolution pores in the lower part, homogenization temperature of the fluid inclusions in the dolomite minerals filled in the dissolution pores increases from 120℃ to 238℃; Average concentrations of Fe and Mn increase from 0.063% and 0.025% to 0.35% and 0.108%, respectively; And δ18OVPDB values decrease from -6.8‰ to -11.2‰. The results of fluid inclusion, element composition and oxygen isotope measurements indicate that the diagenetic cementation in the dolomite reservoirs without bitumen proceeded continuously during deep burial stage. Oil charge altered fluid environment in the dolomite reservoir and thus inhibited precipitation of diagenetic minerals. During deep burial stage, the oil was thermally altered into bitumen that could also inhibit precipitation of diagenetic minerals. Therefore, many dissolution pores could be preserved until present day in the deep dolomite reservoirs with bitumen.