A novel experimental method is proposed to investigate the fluid flow in rotating packed beds (RPB). Experimental results show that the novel method is simple and effective and can be used not only in the lab experimental equipment but also in the industrial grade equipment. By using this method, the hydrodynamic performances of the RPB can be easily studied, which include actual wetting and false wetting, the flow pattern of the liquid film flow, the number and width of liquid trajectories, etc., and consequently, their changing rules are obtained. The results have significant effect on the gas-liquid two phase transfer behavior and are the basis of establishing accurately hydrodynamic mathematical model for RPB.