A wire electrical discharge machine (WEDM) is disclosed, which comprises: a movable crane; a measure unit, mounted on the crane for measuring the deformation of the same; and a control unit, electrically connected to the measure unit and used for controlling the crane to move; wherein a lookup table describing the relation between the crane's deformation and position error is stored in the control unit, basing on which the control unit is able to perform a feedback displacement control on the crane with respect to its deformation.