Main lithologic characteristics, reservoir space and influence factors of Nantun Formation reservoirs in northern Beixixiepo area of Hailar Basin were studied by such means as standardized processing of logging curves and information extraction, observation of rock cores and well log debris, electronic scanning and thin section analysis as well as mercury penetration analysis. The results indicate that Nantun Formation in Hailar Basin is mainly composed of inland lake facies clastic rocks, comprising chiefly breccia, glutenite, conglomerate, grit, fine sandstone,iltstone, argillaceous sandstone and mudstone. The averageporosity of the Nan-1st section reservoir is 6.15%, and the average permeability is 0.31×10-3μm2,uggesting that the reservoir is characterized by low porosity and extremely low porepermeability. The average porosity of Nan-2nd section reservoir is 12.18%, and the average permeability is 2.79×10-3μm2, implying that the reservoir is of mesoporosity and low pore permeability. The reservoir spatial type is of typical intergranular space, with the development of some induced pores. The throat is divided into four types（Ⅰ,Ⅱ,Ⅲ;Ⅳ）. Favorable reservoir sand body types seem to be the fan delta front branch channel sand body, the fan delta plain braided channel sand body and the shore shallow lake sand dam microfacies sand body. The properties of the reservoir are mainly affected by sedimentary facies and diagenesis.