The surface and interfacial tensions without alkali between Daqing crude oil and homemade carboxyl betaine (BC) containing double bond were studied. The critical micelle concentration (Ccmc) of BC was 1.02×10-5 mol/L, and γcmc was 29.603 mN/m at 45°C. When oil and produced water source was the first oil production factory in Daqing, the interfacial tension between BC surfactant solution or BC/0.09% HPAM binary solution with BC concentration of 0.05%—0.20% and crude oil or simulated crude oil reached ultralow level (10-3 mN/m magnitude). The decrease of interfacial tension between BC and simulated crude oil was bigger than that of crude oil. The time to reach ultralow interfacial tension of binary solution was longer than that of single surfactant solution. When oil and produced water source was the third oil production factory in Daqing, the interfacial tension between 0.05%—0.20% BC surfactant solution and crude oil reached ultralow level. Furthermore, 10-3 mN/m magnitude interfacial tension could maintain after 160 days aging at 45℃ which showed good stability of BC.