The volumetric efficiency was adopted to evaluate the overall efficiency of the vane pump used in fuel supply. In order to research the relationship between volumetric efficiency and rotating speed, a corresponding test platform was established. The experimental results show that a phenomenon is appeared that the volumetric efficiency increases for some time, and then declines all the time as the rotate speed keeps increasing. To design the rated speed of the pump according to the characteristics curve between volumetric efficiency and rotating speed will help to increase the efficiency of pumping gasoline in vane pump.