Ethanolamine (ETA) was used together with surfactant to form the ETA/surfactant flooding system. The interfacial tension (IFT) and emulsification of Gudong oil and chemical aqueous solutions were studied. The results indicate that the oil/water IFT can be reduced by 2 orders of magnitude, the oil can be emulsified and dispersed more easily, and the emulsion stability is strengthened due to the synergistic effect of ETA, surfactant, and the in situ soap at the oil/water contact. Seventeen sandpack flooding tests were conducted to investigate the effects of ETA concentration, chemical slug size, chemical slug type, and experimental temperature on the incremental oil recovery. The results show that the highest incremental oil recovery is obtained when 0.065 wt % surfactant and 0.300 wt % ETA are simultaneously injected. In addition, the increase of oil recovery is always accompanied by a sudden pressure drop in the injection process of the ETA/surfactant slug. Larger ETA/surfactant slug size contributes to a higher incremental oil recovery, but there is an optimal slug size (0.8-1.0 PV in the test) when the economic factor is taken into consideration. Moreover, a high experimental temperature has an adverse effect on the synergistic effect of ETA and surfactant because of the volatility of ETA molecules.