The invention discloses a variable-frequency voltage transformation type pure negative ion air purifier. The air purifier comprises a machine shell panel, a machine shell bottom plate, a power adapterand an electrostatic vacuum box, wherein a negative ion generator is fixed between the machine shell panel and the machine shell bottom plate through a negative ion generator fixing plate, a negativeion antenna is arranged on the negative ion generator, the power adapter is electrically connected with the negative ion generator through a power supply jack, the electrostatic dust collection box is buckled below the bottom plate of the machine shell, an electric telescopic rod is arranged in the electrostatic dust suction box, the upper end of the electric telescopic rod is embedded into the bottom of the bottom plate of the machine shell, an electrostatic adsorption net is arranged in the electrostatic dust collection box, an electrostatic generator is arranged in the electrostatic adsorption net, an electric telescopic rod is fixed at the position, corresponding to the electrostatic adsorption net, of the bottom of the machine shell bottom plate, the lower end of the electric telescopic rod is connected with a plurality of umbrella rib-shaped supporting rods, one end of the supporting rod is connected with the electric telescopic rod, and the other end of the supporting rod is supported and connected with the dust sweeping brush, the dust sweeping brush is divided into two parts by an elastic net and corresponds to the inner side and the outer side of the electrostatic adsorption net correspondingly.