A device for controlling screen brightness comprising a light sensor, a comparator and an integrator, wherein the light sensor is configured to acquire a brightness signal intensity value of external environment and transmit the brightness signal intensity value to the comparator; wherein the comparator is configured to compare the brightness signal intensity value received from the light sensor with a stored brightness signal intensity value to obtain a comparison result; wherein the integrator is configured to receive the comparison result, increase the stored brightness signal intensity value by a fixed value, if the comparison result is that the brightness signal intensity value received from the light sensor is greater than the stored brightness signal intensity value, decrease the stored brightness signal intensity value by the fixed value, if the comparison result is that the brightness signal intensity value received from the light sensor is less than the stored brightness signal intensity value, and store the result as the brightness signal intensity value; wherein the stored brightness signal intensity value is configured to control an electric current amplitude of the current screen brightness; characterized in that the device further comprises a consecutive code detector and an amplitude adjuster, wherein the consecutive code detector is configured to receive at least two consecutive comparison results output by the comparator, perform consecutive code detection on the comparison results, and send a consecutive code detection result to the amplitude adjuster; and wherein the amplitude adjuster is configured to increase the fixed value according to the consecutive code detection result, if at least two consecutive comparison results are that the brightness signal intensity value received from the light sensor is greater than the stored brightness signal intensity value, decrease the fixed value according to the consecutive code detection result, if at least two consecutive comparison results are that the brightness signal intensity value received from the light sensor is less than the stored brightness signal intensity value, and send the adjusted fixed value to the integrator. acquire a brightness signal intensity value of external environment and transmit the brightness signal intensity value to the comparator; compare the brightness signal intensity value received from the light sensor with a stored brightness signal intensity value to obtain a comparison result; receive the comparison result, increase the stored brightness signal intensity value by a fixed value, if the comparison result is that the brightness signal intensity value received from the light sensor is greater than the stored brightness signal intensity value, decrease the stored brightness signal intensity value by the fixed value, if the comparison result is that the brightness signal intensity value received from the light sensor is less than the stored brightness signal intensity value, and store the result as the brightness signal intensity value; increase the fixed value according to the consecutive code detection result, if at least two consecutive comparison results are that the brightness signal intensity value received from the light sensor is greater than the stored brightness signal intensity value, decrease the fixed value according to the consecutive code detection result, if at least two consecutive comparison results are that the brightness signal intensity value received from the light sensor is less than the stored brightness signal intensity value, and send the adjusted fixed value to the integrator.