Aiming at the problems of poor injection，low oil washing efficiency and inability of water flooding to improve oil recovery in low permeability reservoirs，a new technology of low interfacial tension small molecule oil displacement agent（LST solution） to improve oil recovery in low permeability reservoirs was proposed. The interfacial activity，viscosity increase， emulsification，wettability，reservoir environment adaptability and oil displacement effect of LST solution were evaluated. The results showed that the displacement agent had good interfacial activity and viscidity. In the mineralized water with salinity of 6788.23 mg/L，the interfacial tension of 0.4% LST solution was 0.012 mN/m，meanwhile the viscosity was similar to that of reservoir crude oil（3.4 mPa·s）. LST solution had good oil-water emulsification ability and could improve reservoir water wettability. The stabilization time of LST emulsion was 120 min at 47.2 ℃ and 1∶1 ratio of oil to water. After the core was treated with LST solution，the water-phase antenna decreased from 57.0° to 12.5°，while the oil-phase antenna increased from 24.3° to 38.6°. LST solution had good static anti-adsorption properties. After three times of core adsorption，the interfacial tension between LST residue and crude oil could still reach the order of 10^-2 mN/m，and then the viscosity could reach 2.895 mPa·s. The water eluting rate of the emulsion after standing for 10 min and 120 min was 38.6% and 73.4%，respectively. The salt resistance of LST solution was good. When the salinity was 16 570 mg/L，the oil-water interfacial tension was lower than 7×10^-2 mN/m and the viscosity was 3.06 mPa·s. LST solution had a good displacement effect，which could effectively plug the high permeability pore and start the residual oil in low permeability pore. Injecting 0.4 PV 0.4% LST solution could increase the water flooding efficiency of homogeneous core（0.05 μm²）by 11.21 percentage points，while the integrated recovery efficiency of heterogeneous core（3— 10 difference）by 6.55—19.41 percentage points. LST solution could effectively improve water drive recovery at low dosage or low cost，which had a good application prospect in enhancing oil recovery by chemical drive in low permeability heterogeneous reservoirs.