The present invention discloses a complex oil displacing method suitable for the large well spacing condition of the offshore field. The saturation relationship curve between the capillary number and the residual oil is produced through the oil displacing experiment for confirming optimization range of the capillary number, and furthermore the oil displacing elements are optimized according to the optimization range. In the process of optimizing the oil displaying elements, the fixed well spacing and the liquid injection speed are confirmed according to the characteristic of the offshore oil field, the underground seepage speed of the part which easily generates the driving state conversion is confirmed with an oil accumulation analyzing method. Then the reference area of the underground working viscosity is generated according to the field construction state. The interfacial tension and the underground working viscosity of the oil displacing system are optimized by the safety factor and the effect coefficient. Finally at the state that the well spacing and the liquid injection speed are confirmed, the complex oil displacing oil production is executed. The complex oil displacing method of the invention can combine the specific construction state for limiting the capillary number to an optimized range for guaranteeing the stability of the complex oil displacing method and a relatively high recovery factor increasing amplitude.