The interfacial tension between methane and aqueous solution with the dosages of 0.25, 0.50, and 0.75 wt % kinetic hydrate inhibitors PVP ramification (PVP-BP) was measured by the pendant-bubble method at 274.9 K and pressures from 0.69 to 11.69 MPa in which 2.35 wt % ethanol was added so that PVP-BP could dissolve in water. The interfacial tension of methane + water was found to decrease sharply with the addition of PVP-BP and reduce with the increase of PVP-BP dosage and pressure. When under the same dosage of 0.S wt % of kinetic hydrate inhibitors, the interfacial tension for system adding PVP-BP is much lower than those adding Inhibex 301, 501, or VC-713, implying much more PVP-BP molecules could be absorbed on the gas-liquid interface. From analyzing the morphologies of oil/water drops and the variation of their size distribution after adding PVP-BP for normal octane + water system with water content of 50, 70, and 90 vol %, PVP-BP was found to have a certain capacity of emulsification like a surfactant.