The reservoir space, properties and main controlling factors of Lower Triassic Jialingjiang Formation in southwestern Sichuan Basin are studied. The result shows that Jialingjiang Formation developed multiple pay formation and reservoir-cap assemblages in the vertical. Because of the difference of developing degree of pore, cavity and fracture, the reservoirs of T₁ j₅¹, T₁ j₄¹and T₁ j₂¹-T₁ j₁¹are mainly fracture-pore reservoir, while the reservoirs of T₁ j₄³、T₁ j₃ are mainly pore-fracture reservoir. The sedimentary facies controls the distribution of favorable lithofacies belt, physical property, the development of secondary pore and reservoir configuration. Dolomization and dissolution control the formation and distribution of secondary pore and cavity, while tectonismaffects the development of fracture. The Daxingchang and Han wangchang structures which are located in the Caledonian palaeohigh ramp region have favorable exploration potential .