Abstract: Optimal control theory is applied to design of contour curves of stator transition zone for a double-acting vane pump.In order to improve characteristics of the pump,a performance index function is proposed in consideration of service life,vibration and noise.An optimal contour curve is obtained from calculation by using Pontryagin's Minimum Principle.The calculated results show that the novel contour curve can effectively decrease the shock and noise in comparison with that designed by polynomial method.It makes a vane pump run at enhanced speed and pressure.Significant improvements are also made in other aspects.Some parameters in the performance index can be adjusted to satisfy special requirements of double-acting vane pump of high performance.