In order to study the influence of capillary number on binary compound flooding system final oil recovery in the heterogeneous reservoir, the binary compound flooding experiments for different viscosities and interfacial tensions are carried out to evaluate the capacity so as to enhance the oil recovery in the heterogeneous reservoir with different capillary numbers(10-6-100)，and the differences of flooding process among different capillary number formulas are compared by microscopic visualization physical model. The flooding result shows that when the interfacial tensions are the same, the higher the viscosity, the higher oil recovery, but there exists a critical viscosity of binary compound flooding. The increment of oil recovery becomes stable when the critical viscosity is reached, and when the viscosity of binary compound system is smaller than critical viscosity, the lower the interfacial tension, the higher oil recovery increment; when the viscosity of binary compound system is higher than critical viscosity, there is a reasonable interfacial tension of binary compound system, and the oil recovery reaches maximum at the reasonable interfacial tension (1.865×10-2 mN/m). The oil recovery reaches the highest at critical viscosity and reasonable interfacial tension, and the reasonable capillary number is obtained. The microscopic visualization physical simulation experiment shows the reasonable capillary number formula. The formula with this capillary number has certain oil-washing ability，besides, the emulsion formed with this formula has profile control capacity on the target reser?voir.