Aiming at the problems such as high water injection pressure and severe shorting-injection resulting from the low porosity and low permeability in low permeability sandstone reservoir, the cationic surfactant with amide groups (BNFS) whose name was molecular injection agent was developed. The adsorption property, wettability, surface and interfacial activity, and drag reduction performance of BNFS was evaluated. The results showed that a layer of molecular film formed after BNFS absorbed on the sandstone surface. The contact angle of sandstone surface was increased from 27.6° to 88.6°, and the wettability of that changed from strong water wetting to slight water wetting. When the concentration of BNFS was 200 mg/L, the surface tension of solution was 26.61mN/m and the interfacial tension with kerosene was 0.06 mN/m. The core flooding experiment results showed that water phase permeability of sandstone core increased 80%—120% and water injection pressure decreased 12%—18% by BNFS. The analysis result of molecular injection mechanism showed that the magnitude order of adsorption energy was 10-18 J between molecular injection agent and hole wall, and that was 10-20 J between water molecule and hole wall. The adsorption energy of former was far greater than that of latter. Therefore, molecular injection agent had absolute advantage in the competitive adsorption to make effective seepage channel increase. The adhesion work between core and water molecule reduced from 136.5 mN/m to 75.7 mN/m after BNFS applied to core, which showed obvious drag reduction.