A control circuit applied to a lifting platform controls a motor to adjust the height of a platform. The control circuit includes an AC/DC conversion circuit, a DC/DC conversion circuit, a detection unit, and a control unit. The detection unit detects an output end of the AC/DC conversion circuit and provides a detection signal. The control unit provides a PWM signal according to the detection signal to control the DC/DC conversion circuit so that the DC/DC conversion circuit converts a DC voltage to an output voltage. When the control unit realizes that the DC voltage or a DC power provided by the AC/DC conversion circuit is less than a power supply threshold according to the detection signal, the control unit decreases a duty cycle of the PWM signal to maintain the DC voltage or the DC power to be greater than or equal to the power supply threshold.