A handheld electronic device is provided. The handheld electronic device includes a screen, a back cover, a frame, a main board, and a heat conduction structure. The frame is arranged between the screen and the back cover. The frame and the back cover define a space. The main board is arranged in the space, and includes a front surface and a back surface. The front surface faces the screen and includes a heat source. The heat conduction structure extends from the front surface to the back surface, and includes a first end and a second end opposite to each other. The first end is arranged at the heat source, and the second end extends to the back cover.