Abstract: Analyzed geology, develop dynamics and reservoir characteristics of hot water injection block of B125 block on Gucheng oilfield, laboratory experiment was developed by surface acting agent in order to improving recovery ratio. Based on the research of compatibility of surface acting agent with field water, experiment of emulsify and testing of surface and interfacial tension, select surface acting agent which adequate for B125 block, oil disperse experiment and precursor testing scheme were designed. Results shows that surface acting agent HPS-3B, HPS-3C can obviously improve heavy oil recovery ratio.