Aiming at the problem of water injection in the injection well of Longdong oilfield，the cationic-gemini surfactant compounding system XG-D was prepared using cationic surfactant cetyltrimethylammonium bromide and bisphosphonate dimeric surfactant XG as raw materials. The performance of XG-D was studied by oil-water interfacial tension and wetting performance test and indoor core flooding. Finally XG-D was applied in Longdong oilfield. The results showed that XG-D had good compatibility with simulated formation water. 0.25% XG-D could reduce the oil-water interfacial tension to 0.01 mN/m，indicating good performance on reducing oil-water interfacial tension. XG-D had better salt tolerance. XG-D could adsorbed on the surface of oleophilic mica，transforming the hydrophilic surface of solid into a weak hydrophilic surface with good conversion. The results of core flooding experiments showed that XG-D had better depressurization and injection characteristics，which could reduce the water injection pressure by 49.88% and increase the oil displacement efficiency by 6.4%. The field application results showed that XG-D could be used to achieve the pressure reduction and injection increase in the high pressure injection well of Longdong oilfield.