A controlling method for an electronic device is provided, including the following steps: receiving a feedback signal; determining a signal strength value of the feedback signal; obtaining a first threshold value and a second threshold value; comparing the signal strength value with the first threshold value and the second threshold value, where the first threshold value is less than the second threshold value; controlling a screen to operate in a first mode when the signal strength value is greater than the second threshold value; comparing the signal strength value with a predetermined value when the signal strength value is greater than the first threshold value but not greater than the second threshold value, and adjusting the first threshold value to be the signal strength value when the signal strength value is greater than the predetermined value.