An electronic device includes a base and a sidewall attached to the base. The sidewall includes a heat dissipating area defining a plurality of vents, a sliding plate slidably coupled to an inner side of the sidewall, and a controlling arm made of metal material having high coefficient of thermal expansion. The controlling arm is connected between the sliding plate and the sidewall, for driving the sliding plate to slide to cover or uncover the vents of the heat dissipating area according to different interior temperature of the electronic device.