When using displacement experiment to evaluate polymer/surfacant displacement formula system，due to the degassing and dehydration of ordinary heavy oil after recovery，As a result，the viscosity of the oil used in the oil displacement experiment is too high to be used for physical simulation of oil displacement experiment to evaluate the oil displacement formula system. In addition，after the oil displacement system is injected into the formation， it will be subjected to dilution，shear and other effects，resulting in a significant decrease in viscosity，which requires a reasonable design of the viscosity of the oil displacement system when injected into the wellhead. Therefore，for the common heavy oil reservoir of H1 block，the viscosity design method of oil displacement experiment is studied. High pressure physical property method was used to determine the viscosity of crude oil for oil displacement experiment，and the viscosity design method of oil displacement formula system was determined by comparing the oil displacement efficiency of different viscosity systems. The polymer concentration was determined by this method，the polymer/surface displacement formula system was optimized，and the oil displacement efficiency was predicted to be 28.3% higher than that of water flooding，providing a technical alternative for common heavy oil reservoirs to carry out polymer/surfacant combined oil displacement experiment.