The invention discloses an intelligent power supply switching device, a power supply system applying the same and a control method. The intelligent power supply switching device comprises a switching strategy generation module, a direct current measurement module, an alternating current measurement module and a composite switching module, wherein the switching strategy generation module is respectively connected with and controls the direct current measurement module, the alternating current measurement module and the composite switching module, and the composite switching module is connected with the alternating current measurement module. The beneficial effects are that trouble-free switching between an off-grid solar energy inverter and the mains supply is realized, and the power utilization safety is ensured. Meanwhile, the utilization rate of solar energy is improved, and the energy is saved.