A wide load characteristic ZVZCS three-level DC-DC converter relates to a three-level converter. The aim of the invention is to settle the problems of large switching loss, generation of large voltage peak, easily switching tube damage and series electromagnetic interference problem existing in the prior three-level converter. The anode of a voltage source is simultaneously connected with one end of a first capacitor, one end of a fifth capacitor, a drain end of a first insulated-gate type field effect transistor, the cathode of a first diode, the cathode of a fifth diode and the collector electrode end of a fifth triode. The cathode of the voltage source is simultaneously connected with one end of a fourth capacitor, one end of the sixth capacitor, a source end of a fourth insulated-gate type field effect transistor, an anode of a fourth diode, an anode of a sixth diode and the emitter end of a sixth triode (S6). The wide load characteristic ZVZCS three-level DC-DC converter of the invention is also added with an auxiliary rectifying circuit and an active clamp circuit. The wide load characteristic ZVZCS three-level DC-DC converter of the invention has the advantages of high resetting speed of the primary side current, no overshoot voltage of the secondary side, etc. Furthermore the wide load characteristic ZVZCS three-level DC-DC converter of the invention settles the problems of duty ratio loss, primary side circumfluence, parasitic oscillation, etc. The efficiency of the converter is increased. The switching loss and the electromagnetic interference are reduced.