Abstract: Based on the experiments of static tight sandstone soaked in CO2-saturated brine and indoor fracturing simulation, the influence of CO2-brine-rock interaction on tight sandstone properties and hydraulic fracture propagation were studied, and the special chemical effect of CO2 was simulated by soaking the open-hole section of fracturing sample in CO2-saturated brine. The study results show that after soaking in CO2-saturated brine, the contents of calcite and dolomite in the rock sample significantly decrease, kaolinite occurs after the corrosion of potassium feldspar and anorthose; the contents of quartz and clay minerals increase and those of illite and chlorite decrease; the amount of dissolved pores rises, the pore diameter, porosity and permeability become larger; the tensile strength of the tight sandstone decreases, and the decrement extent of the tensile strength in parallel bedding is larger than that in vertical bedding; compared with slickwater fracturing, the formation fracture pressure of supercritical CO2 fracturing reduces by 14.98% and the number of hydraulic fractures increases. After the openhole section soaking in CO2-saturated brine, the formation fracture pressure of supercritical CO2 fracturing decreases by 21.61% compared with that of supercritical CO2 fracturing without the soaking treatment and the fracture complexity is greatly enhanced. The experiment result proves that the physical and chemical properties of CO2 can effectively improve the fracture complexity during CO2 fracturing