The dual transformation topology structure is adopted, the input is equipped with harmonic suppressor, the inverter is SPWM pulse width modulation technology, IGBT power module, and the output is equipped with isolation transformer to provide a sine wave power supply with stable frequency and voltage, no interference, pure and low distortion for the load. It has the characteristics of strong load carrying capacity and good compatibility, and meets the requirements of high reliability, high stability and high quality of uninterruptible power supply in various industries.