In order to solve the problem of microbial flooding in Shengli Oil Field, the efficient microbial SZ2 was cultivated by using glucose, peptone, yeast extract, dipotassium hydrogen phosphate and sodium chloride. The effects of microbial SZ2 on the viscosity, composition, oil-water interface properties, emulsifying properties and wettability of crude oil were analyzed by high temperature and high pressure rheometer, bar thin layer chromatograph, spinning drop interfacial tensiometer and dynamic contact angle measuring instrument, and the interface effect of microorganisms was studied. The results showed that the microbial SZ2 reduced the viscosity of crude oil from 1197mPa·s to 432.7mPa·s at 60℃, and decreased 63.9 %, and the mass fraction of glial and asphaltene decreased from 70.34% to 67.16%, decreased by 4.5% under normal temperature(20℃). The interfacial tension of the formation water (salinity: 10220mg/L) and heavy oil (7945mPa·s) was reduced from 40.96mN/m to 16.72mN/m, which was 59.18% lower than that of deionized water at 55℃. The contact angle decreased from 81° to neutral 20.28° at 60°C and crude oil was completely dispersed for 10 days. The performance of the crude oil was better than that of Shengli Oilfield. In Shengli Oilfield, during the field test, the comprehensive moisture content of the oil wells was reduced from 96.1% to 89.1%, and the cumulative yield was 3288t. The effect was good and the application prospect was broad.