A three-level converting circuit, and a starting method and electronic equipment thereof. The circuit includes: a first voltage source; a first soft-start circuit; a first capacitor; a first switch, a second switch, a third switch and a fourth switch sequentially connected in series; a flying capacitor; a second soft-start circuit; a second voltage source and a second capacitor. The three-level converting circuit can pre-charge the flying capacitor, the first capacitor and the second capacitor when executing the starting method thereof, thereby preventing the over-voltage damage of the switches.