The invention provides a method for horizontally controlling upper and lower working rolls of a Steckel mill. The method comprises the following steps that 1, the set value of a roll gap is set in advance; 2, the pressure on strip steel on the working side and the pressure on the strip steel on the driving side are measured by a pressure sensor, pressure data are fed by the pressure sensor back toan industrial computer, and the pressure difference between the two sides is calculated by the industrial computer; 3, the pressure difference is fed back to a servo valve, the servo valve acts to drive an AGC hydraulic cylinder piston to act, a lead screw is driven by the piston to move, an upper supporting roll is driven by the lead screw to move, and the upper working roll synchronously movesalong with the upper supporting roll; 4, displacement information of the piston is fed back to a displacement sensor, a displacement signal is transferred to a controller and compared with the set value of the roll gap, the action of the piston is stopped if the displacement signal is equal to the set value of the roll gap, and the displacement of the piston continues to be adjusted through a closed-loop system so as to adjust the roll gap to reach the set value if the displacement signal is not equal to the set value of the roll gap; and 5, the pressure on the working side and that on the driving side are repeatedly measured by the pressure sensor till the detected pressure data are equal. The method provided by the invention has the beneficial effects that when the temperature of the head part of the strip steel and that of the tail part of the strip steel are reduced, the rolling reduction of the hydraulic cylinder is quickly adjusted according to the pressure difference between theworking side and the driving side, thereby ensuring that the belt steel is protected against deflection and avoiding the abnormal shutdown.