Abstract: The reservoir of the 3rd member of Xujiahe formation in Yuanba area is tight sandstone reservoir with low porosity and low permeability. Based on the core，logging and geological data, the features of fracture development on the core and the response of fractures on the conventional well logging are studied, and the regional geological structure setting is used to research the control factors of fractures, by which the fracture development of the 3rd member is evaluated comprehensively. The study shows that the type of fracture origin belongs to structural fracture dominated by low?angle or horizontal tension fracture, with high effectiveness of it. The fractures are mainly manifested as high interval transit time and low dual laterolog resistivity by conventional well logs, and relatively large width and porosity by log interpretation. Combined with the regional geologic data, the core observation and the fracture logging identification results, the fracture development is affected synthetically by layer thickness, fault, lithology and structural deformation intensity. Finally, according to the factors controlling fracture development, by using precision grid to evaluate the fracture in the Yuanba area, the results are in good accordance with the conventional single well identification result at the rate of 87.9%, and also good with the production test result