An integrated-type high step-up ratio DC-AC conversion circuit with an auxiliary step-up circuit applies to converting a low DC voltage of alternative energy into a high AC voltage. The conversion circuit uses an isolated Cuk integration unit and an auxiliary step-up unit to form a multi-phase input and uses parallel charging and cascade discharging to boost the DC voltage in the DC side with a low voltage power switches and low duty cycle and then converts the boosted DC voltage into AC voltage. The auxiliary step-up unit not only shares the entirety of power but also exempts the DC-side circuit from using high voltage power switches, whereby the cost of elements is reduced. Further, the conversion circuit can decrease the switching loss and conduction loss of the DC-side switches and promote the efficiency of the circuit.