Abstract: The sand body of upper Wuerhe formation of Zhongguai uplift has the characteristics of big thickness, strong heterogeneity and great productivity difference between adjacent fault blocks. In order to analyze the low production factors in 598 fault-block, the data of mud logging, gamma logging, core, rock thin sections and analytical analysis were applied to conduct a comparative study on petrology, physical properties, reservoir space, pore structure characteristics and oil-gas bearing characteristics of adjacent wells with obvious productivity differences in 598 fault-block. The results show that the reservoir rock of low production wells in 598 fault-block is of strong plasticity, and the clastic particles are mainly in linear contact with each other, low porosity and permeability, and poor relationship between pore throat configuration. Poor reservoir physical properties and complex pore structure are the fundamental factors of low production. The high content of clay minerals and the presence of water sensitivity are important factors for low production. Poor hole throat configuration, micro-roar development, formation energy loss and water lock effect near the wellbore are important factors that cannot be ignored.