Abstract: The through-flow characteristics of the rotary tube was studied. Based on the fluid mechanics, the analytical model of the system was built. The through-flow characteristics of the rotary tube and the influencing factors were investigated in experiments. The results indicate that the flow rate of rotary tube changes with speed and oil pressure changes. In the early stage of speed increasing, flow rate change is small. As the speed increases, the weakening trend of flow ability also increases. The through-flow characteristics are positively correlated with size and number of the flow orifice. The outer diameter of the flow orifice has an effect on the centrifugal pressure and oversized outer diameter will cause oil inlet difficulties at high speed. It is necessary to consider the effects listed above in the lubrication system design of the high speed planetary transmission.