The present disclosure provides a method for turning on an air conditioner and a device for turning on an air conditioner, belonging to the field of smart home. The method includes: acquiring a sensor parameter collected by a sensor in a wearable device; determining a physiological parameter based on the sensor parameter; determining a change in a sleep state of a user wearing the wearable device based on the physiological parameter; detecting whether the change in the sleep state is in conformity with a predetermined condition; and turning on the air conditioner when the change in the sleep state is detected to be in conformity with the predetermined condition.