Aimed at the problems ofwater injection displacement for lowpermeability reservoir in DaqingOilfields, such as high water injection pressure, lowwater injectivity and lowoil recovery, a laboratory experimental study is conducted for displacing crude oil in LonghupaoOilfield by active water flooding. Surfactant screening result shows that the interface tension of active water/crude oil system, where sodiumdodecyl benzene sulfonate （SDBS） is used as surfactant, can reach 2.041×10^{- 1} mN/m. SDBS has good compatibilities with formation water and the active water flooding can reach an oil recovery increment of 16.6% higher than that ofwater flooding. The result of oil displacement experiment shows that active water injection rate, activ e water concentration and active water injection amount have effects on oil displacement efficiency, of which the optimal values are 1.0 mL/min, 0.3% and 0.3 PV respectively. Active water injection timing also has some influence. Oil production wells with lowwater content should be chosen to carry out active water flooding in situ and active water concentration should be augmented when water content increases.