Based on the pore cast and cathodolumines-cence thin sections, diagenesis process, source rock matura-tion history, structural evolution and reservoir quality characteristics, the points of view that the porosities of Pa-leozoic clastic eureservoirs in the platform of the Tarim Ba-sin are mainly secondary, and the dissolution plays an unignorable role in the formation of eureservoirs, are put forward. In this paper, a series of criteria for the recognition of the secondary porosities, the occurrence extent and classi-fication of secondary porosity are introduced, and three kinds of dissolution mechanism--the aluminosilicate dis-solution, the silicon dioxide dissolution and the carbonate dissolution--to generate the secondary porosity are come up with. The formation, distribution, preservation and dis-appearance of eureservoirs are controlled by the paleo- structural framework and evolution, and hydrocarbon filling and discharging. Paleostructural framework manipulate the migration path and direction of the acid fluid so as to deter-mine the position and extent of the dissolution. Paleostruc-ture highs and continuous paleouplifts are in favor of devel-oping the secondary porosity. The hydrocarbon filling made the secondary porosities preserved and the hydrocarbon discharging let the secondary porosities filled by later calcite or quartz overgrowth cements. Paleostructure highs and continuous paleouplifts during the maturation period of Cambrian, Ordovician and Carboniferous source rocks (corresponding to S, P and K) are main areas for eureservoirs developing.