Big radius arc of stator curve in intra-vane type pump was replaced by an equal velocity curve whose radius was changed according to rotation angle. And advance rising pressure of oil in working room, contract force of vane and flow characteristic of pump were studied for intra-vane type pump. It is found that the amplitude of advance rising pressure of oil in working room was decreased after the rotor rotated 2°from the beginning of transition curve of vane pump when the big radius arc of vane pump stator curve was replaced by equal velocity curve. When the value of variable radius between the beginning and end of equal velocity curve was 0.1mm, the contract force of vane could be decreased by 160N and the rate of flow decreased by only 10－4m3/s. So the improved stator curve has little influence on flow characteristic, and the condition of dynamics characteristic of vane can be improved, with which the abrasion of vane and noise of pump can be reduced.