Palaeo karstification can form the potential oil and gas reservoirs. Guiding by the outcrops in north Tarim Basin, the reservoirs framework elements and its identification methods are analyzed, including underground river cave, longitudinal cave, cave hall and cave controlling faults, and taking the S48 unit of 4th block in Tahe Oilfields as example, development characteristics including geometry dimension and assembly of elements are described. Research shows that, the underground river caves have the largest scale, and difference between longitudinal cave and isolated cave hall is the height diameter ratio. Different caves have a variety of combination way, and cave controlling faults are important connection ways. Matching number of 3 kinds of cave and fault reached to 2.5, 1.9, 1.7, and cave development and faults distribution have good coupling relationship. In addition, the paleogeography controls karst development to a certain extent too.