In order to achieve the effect of decompression and augmented injection, sulphonate surfactant was adopted to reduce IFT between oil and water by Taibei SII group, which required optimizing and adjusting formulation of surfactant. The variety and concentration of alcohols and salt assistants were screened to reduce IFT of oil-water interface, and test of evaluation on surfactant resistance was used to highlight its characteristics and the optimal application conditions. The results show that the effect of mixed reagent of 0.1%~0.8% ethanol, normal butyl alcohol and sulphonate outperforms that of methanol, normal propyl alcohol and glycerin. With increase of salt concentration, the surface tension first descends and then rises, showing a L-shaped curve. The surfactant has better activity on formation of 50 ℃ within 15 d. The influence of mineralization degree on IFT between oil and surfactant approximates to "Ω" shape. The slightly alkaline condition is favorable for the action of surfactant. Core displacement test shows that optimized surfactant can achieve 18.7% depressurization, and the effect is better.