A step cavity type low frequency ultrasonic atomization nozzle with a swirlable vortex impeller, has an air intake casing, an inlet casing, a Laval core, a fixed cap, an adjustable pedestal, and taper rectifying sleeve, swirlable vortex impeller, stepped resonance tube, regulative plunger, positioning lead, second pedestal. The regulative plunger is located in the second stepped hole of the stepped resonance tube, and its axial position is adjustable; the swirlable vortex impeller is fixed on the taper resonance tube through the bearing, and the outer cone surface is matched with the inner cone surface of the taper rectifying sleeve. The resonant cavity is improved so that the two-phase fluid in the cavity can generate higher frequency and greater fluctuation of the pressure fluctuation amplitude, optimize the initial atomization performance of the nozzle, and optimize the nozzle outlet, and increase the swirlable vortex impeller.