The invention discloses a control method for a cleaning device, comprising the step of providing the cleaning device comprising a control unit, a fan module and an opto-sensor, wherein the opto-sensor is positioned on the air inlet of the fan module; the control unit is preset with a first impedance value Z1, a second impedance value Z2 and a critical value of light intensity, wherein Z1 is less than Z2 and more than 0; then, the control unit reads an impedance value Z of the fan module; if Z is less than Z2 and more than Z1, the control unit drives the fan module; if Z2 is less than Z, the control unit reads one detection value of the opto-sensor by the control unit; if the detection value is more than a critical value of light intensity, the control unit drives the fan module so as to increase the attractive force of the fan module; and if the detection value is less than the critical value of light intensity, the control unit closes the fan module.