Tight sandstone reservoirs have been a research focus of many scholars around the world in recent years. The tight sandstones of Chang81 member，as the most important pay bed of Honghe oilfield，mainly consist of feldspathic litharenite and lithic arkose，which are extra-low porosity and permeability reservoirs and are difficult to be explored and developed. The diagenetic events and the reconstruction of diagenetic sequence and porosity evolution history of Chang81 tight sandstones were analyzed and made clear by using an integrated approach of casting thin-section，cathode luminescence，rock pyrolysis，clay X-ray diffraction，capillary pressure curve test and reservoir sensitivity test. The results show that the tight sandstones of Chang81 member are currently in the stage A of mesodiagenesis，and they have mainly suffered from mechanical compaction，cementation and dissolution. About 50％of original porosity has been destroyed by the mechanical compaction and about 30% of original porosity is filled by calcite and kaolinite cements. However，the dissolution can improve the reservoir physical property to some extent. Reservoir space are characterized by intergranular dissolution pores，residual primary pores and microfractures. The pore throat structure is characterized by fine throat，micro-fine throat and micro throat and reservoir with fine throat is the target area for the next step of exploration and development. The reservoir sensitivity to flow velocity is medium-weak；its sensitivity to salt is medium；its sensitivity to water or to alkali is weak. It is not sensitive to acid. Its sensitivity to stress is also weak. The reservoir sensitivity experiment provides an important basis for reservoir stimulation and water flooding.