Abstract: Euler-euler two flow model was applied to simulate the effect of nozzle diameter and nozzle position on the hydrodynamics in airlift loop reactor in the oil-hydrogen system to provide theoretical guidance for suspension bed industrial equipment. The simulation results show that related to the nozzle diameters of 40 mm and 80 mm, the circulation power is larger when nozzle diameter is 20 mm; the liquid circulation velocity in the rising and dropping is larger, but the gas holdups change small. The gas holdup when the nozzle was set at higher location is obviously higher than that of the gas holdup at the horizontal and low location, while there is not much difference of gas holdup between the horizontal and low location. The liquid circulation velocity magnitudes at three nozzle locations are: low>flat>high location. It is concluded by comprehensive consideration that the flow characteristics is better when the nozzle diameter is 20 mm at low location.