Abstract: Based on study of Paleozoic carbonate reservoir rock in the Tarim Basin,it is discussed in this paper reservoir rock type,reservoir room type,reservoir capacity and carbonate rock diagenesis.Paleozoic carbonate reservoir rock in the Tarim Basin can be classified into 4 types: ancient karst and weathered residuum,shoal and reef,oolitic beach and dolomite.5 stages of tectonic evolution result in 5 stages of ancient karst reservoir,including: Lower Cambrian-Upper Sinian,Middle Ordovician-Upper Ordovician,Silurian-Ordovician,Carboniferous and underlying strata,and ancient karst between Triassic and Pretriassic.Reservoir room is divided into 2 types: pore-vug and fracture.Pore and vug include micropore,intercrystalline pore,dissolution pore and dissolution vug.Fractures include diagenetic fracture,facture related to regional tectonics,fracture related to fold,fracture related to rupture,and fracture related to deep strata charge and pore pressure.Diageneses of carbonate reservoir rock include compaction,pressure solution,cementation,dolomitization,recrystallization,silicification and dissolution.Reservoir rocks include dolomite(fracture-vug type) and limestone(fracture type,with few vug-fracture type and fracture-carven type).Reservoir capacity of dolomite is much better than that of limestone.