A switched-mode power supply (SMPS), capable of catching radiated electromagnetic interference (EMI) and using its energy, includes a specific component, an antenna, a rectifier, and an energy storage capacitor or a rechargeable battery. The specific component generates radiated EMI. The antenna is disposed on or embedded in the specific component, and the frequency range of the antenna corresponds to the frequency band of the radiated EMI generated by the specific component. The rectifier is electrically connected with a terminal of the antenna. The energy storage capacitor or the rechargeable battery is electrically connected with the rectifier. The SMPS may simplify the design of circuits for suppressing radiated EMI to reduce cost, and to achieve the purpose of power saving by recycling and reuse of dissipated energy.