A power switching circuit of a portable electronic device is disclosed. The portable electronic device can be coupled to an expansion device. The power switching circuit includes a first power terminal, a second power terminal, a first switch module, a second switch module, and a power pin. The first switch module is coupled to the first power terminal. The second switch module is coupled to the second power terminal. The power pin is coupled to the first switch module and the second switch module, respectively. When the portable electronic device is not coupled to the expansion device, the first switch module and the second switch module are turned off, such that first power provided by the first power terminal and second power provided by the second power terminal fail to be provided for the power pin via the first switch module and the second switch module.