A single method is difficult to comprehensively and accurately characterize pore structure of tight oil reservoirs, for which exhibit strong heterogeneity and complex microscopic pore structures. In order to clarify the micro pore structure characteristics of tight oil reservoirs, and provide important geological guidance for their exploration and development, reservoirs including tuffaceous sandstone, dolomitic sandstone, and glutenite reservoirs of Fengcheng Formation in the Mahu Sag, Junggar Basin were focused on. Core analysis, X-ray diffraction (XRD), cast thin sections, fluorescence thin sections, scanning electron microscopy (SEM), high-pressure mercury intrusion (HPMI), and nuclear magnetic resonance (NMR) were used to evaluate the type of high-quality tight oil reservoirs. The results show that tuffaceous sandstone and dolomitic sandstone reservoirs are dominated by intergranular dissolved pores, secondary are intragranular dissolved pores, intercrystalline pores, micro-fractures, and residual intergranular pores; Meso-pores are predominant, and connectivity is relatively poor. Glutenite reservoirs show a slightly higher proportion of intragranular dissolved pores, secondary are residual intergranular pores, intergranular dissolved pores, and micro-fractures having similar proportions; Meso-pores and Micro-pores are predominant, and connectivity is relatively better. Based on centrifugal-NMR experiments, the average oil recovery efficiency was found to be 46% for glutenite reservoir samples, 30% for tuffaceous sandstone samples, and 32% for dolomitic sandstone samples. It is concluded that the glutenite reservoirs are identified as the key target for the next phase of tight oil exploration.