Abstract: A portable electronic device with a battery switching function is provided. The portable electronic device has two battery switching assemblies corresponding to each battery. Each battery switching assembly has a primary fastener and a secondary fastener corresponding to each other. When the primary fastener is engaged with the secondary fastener, the secondary fastener engages with the corresponding battery so that the battery cannot be detached from the casing of the portable electronic device. When the primary fastener and the secondary fastener are disengaged, the Hall sensor corresponding to the primary fastener sends a signal to a control unit. Then the control unit turns off the power supply of the corresponding battery and switches to another battery to supply power, or closes a specific application to reduce power consumption.