Abstract: Disclosed herein is a portable electronic device including a main body and a fan. The main body includes two opposite first and second lateral housing surfaces. The first lateral housing surface includes a first air outlet, and the second lateral surface comprising a first air inlet. The fan is disposed within the main body and includes a ventilation outlet and a ventilation inlet. The space layout within the main body includes at least an air channel interconnected between the air inlet and the ventilation inlet, wherein the air channel includes an second air inlet and an second air outlet; furthermore an cross-section of the second air inlet is smaller than an cross-section of the second air outlet.