A drag reduction mean which consists a duct and a support mean which duct can reflect passed through flows and which is mounted on one end of the support mean which another end can be mounted on an object which can move in a fluid; the length of the support mean being able to be altered by a mechanical mean; the ratio of the cross-sectional areas of the entrance and the exit of the duct being able to be altered; the normal directions of the exit of the duct being able to be altered; the algorithms of using the drag reduction means being revealed.