A method for controlling a transmission device of a vehicle. The device includes a hydraulic transmission. The displacement of the hydraulic pump is controlled so that it delivers to the n hydraulic motors a constant flow that is proportional to the speed of the wheels rotated by the drive. The displacement control of the hydraulic pump is carried out by a correction constant and a correction variable. The correction variable is determined in real time. The correction constant includes the sum of a theoretical constant and an adjusted constant. The theoretical constant is defined according to the theoretical behaviour of the hydraulic transmission. The adjusted constant is defined and corrected when the vehicle is in predetermined conditions of use, in order to reflect the real state of the vehicle.