The invention relates to a deformable rudder, which comprises a rudder head, wherein the end part of the rudder head is rotatably connected with a plurality of middle rudder bodies and a rudder tail through rotary shafts to jointly form multiple sections of flexible rudders; each rotary shaft is independently provided with an oscillation mechanism; a driving mechanism is installed in a rudder frame and comprises a motor; the output end of the motor is connected with each oscillation mechanism in sequence through a universal spindle coupling; two adjacent oscillation mechanisms are connected through the same universal spindle coupling by a lead screw; the motor rotates, the lead screw in the oscillation mechanism is driven through the universal spindle coupling to rotate so as to drive screw pairs cooperated with the lead screw to axially move along the lead screw; in a screw pair movement process, through connection pieces swing relative to the screw pair through a hinge pin; and the rotary shafts swing along with the through connection pieces, so that the adjacent sections of the rudder connected with the rotary shafts deflect, and therefore, the appearance of a rudder surface changes. By use of the deformable rudder, the continuous and smooth change of the arch camber of the rudder surface is realized, the lift coefficient of the rudder is effectively improved, and therefore,the maneuvering performance of the ship is greatly improved.