Abstract: The accommodation spaces of the Upper Cambrian strata in Wulong, eastern Chongqing consist dominantly of secondary porosity such as intercrystal pores, intercrystal solution openings, intragranular solution openings, intergranular solution openings, cast pores, caves and fissures. Diagenesis is considered as a principal factor affecting the reservoir capacity, and may be divided into two types:constructive and destructive. The former includes dolomitization, dissolution and fracturing while the latter comprises cementation, compression and pressure-solution, and filling.