Abstract: As for the challenges of heavy oil gathering and transportation in China's oil fields at high water-cut stage, the cyclone field with low shear strength was constructed, the cylindrical cyclone separator was used for oil-water pre-separation, and the numerical simulation method was adopted for research. The Mixture model and RNG k-ε model were used to numerically simulate the cyclonic separation characteristics of heavy oil, so as to investigate the effects of dispersed phase particle size, oil viscosity, density, split ratio and inlet flow rate on the oil content at the outlet of underflow and pressure drop at the outlet of overflow. The results show that the separation characteristics of heavy oil in cylindrical cyclone differ from those of other oils. The oil content at the outlet of underflow is significantly affected by the particle size of dispersed phase, but the pressure drop is rarely affected. The effects of oil density and viscosity on the oil content at the outlet are quite different, and there should be an optimal separation viscosity zone (750-830 mPa·s) within the research range of the selected viscosity. Oil content at the outlet of underflow decreases with the increase of inlet flow rate. Split ratio has little effect on pressure drop, and the simulation results are consistent with the existing experimental results.