Based on cast thin section, scanning electronic microscope and mercury penetration curves, the petrological characteristics, pore type, pore texture characteristics, reservoir properties and influencing factors of Chang 6₁¹ reservoir are systematically studied, and the favorable exploration target areas are pointed out. Through the comprehensive evaluation, it is considered that arkose is the main sandstone type of Chang 6₁¹ reservoir, and the pore types include primary intergranular pore, dissolved intergranular pore, dissolved intragranular pore and micro-fracture. The plane porosity of cast thin section of the sandstone reservoir ranges between 0.98% and 1.37%, the average throat radius is low, and the reservoir is of typical middle-low porosity and low permeability. The main factors that influence the reservoir properties are sedimentary environment and diagenesis.