Abstract: Aiming at the slow dissolution and ideal performance of long time of drilling fluid materials, the surface active agent is suggested to reduce the tension and contact angle of water's surface At the same time, the surface active agent has wetting and solubilization effect on materials. Through the analysis on the mechanism of surfactant and testing the influence of surface active agent on the basic properties of drilling fluid, the surface active agent is optimized. Observing the influence of surface active agent on soil (Shanghai Jiayou soil, Ezhou soil and alkaline soil) and high molecular material performance helps to optimize dosage of the surfactant. The results show that lecithin 1 has the best effect to promote hydration dispersion of the material in short period of time and optimal dosage is 0.2 ‰. For the 6% of Shanghai, Ezhou, Jiayou soils, the apparent viscosity increased respectively by 20%, 20% and 6%. 0.2 ‰ of lecithin can promote the formula (4% Jiayou soil +1 ‰ XC+0.8%DFD), the apparent viscosity increases by about 15%, lubrication increases by 37%, the surface tension decreases by 42%. High molecular material is more evenly dispersed and drilling mud cake is more dense.