Based on the study of a patent, the configuration and action principle of a new variable displacement of double-action vane pump is discussed. The pump is equipped with floating blocks that may move up and down in accordance with the rotational speed of the pump. The pump belongs to an automotive hydraulic power steering system. The mathematical and simulation model for the hydraulic power steering of an automobile was established. Different pump parameters were selected for simulation. The simulation results showed that the pump with the floating block can provide power characteristics are better than a common pump. The utilization of the proposed pump is expected to improve efficiency and decrease exhaust gas and noise.