The invention discloses an air plasma cutting machine, comprising a main circuit and a control circuit. The main circuit is composed of a superior main circuit and an inferior circuit which are connected in series. The superior main circuit is composed of an alternating current (AC) power source, an input rectifying wave filter circuit and a full bridge inverter circuit which are connected in series. The inferior main circuit is composed of an output rectifying wave filter circuit, a high power switch circuit and an output resistor. The control circuit is composed of a superior control circuit and an inferior control circuit, wherein the superior control circuit is connected with the full bridge inverter circuit through a superior frequency determining and pulse-width determining circuit and a superior drive circuit which are in series connection. The inferior control circuit is composed of a current detecting circuit, a given circuit, a comparison amplifying circuit, a PWM circuit and an inferior drive circuit, which connects the current detecting circuit with the comparison amplifying circuit. Under the mutual function of the superior inverter and the inferior chopper, the invention can obtain an external feature of constant current and a good dynamic feature; thereby obtaining a high-quality welding seam with small volume, light weight, convenient movement, material saving, and high efficiency and energy reserving.