The utility model discloses a negative ion air purifier, comprising an electrostatic field-generating module and a voltage boost circuit. The voltage output end of the voltage boost circuit connects with the voltage input end of the electrostatic field-generating module. Said electrostatic field-generating module includes anodes and cathodes that are arrange alternately and equidistantly. A frequency conversion and voltage regulation module is further added, whose voltage signal sampling end connects with the voltage output end of said voltage boost circuit and whose control end connects with the voltage signal input end of said voltage boost circuit, thus making the device adapted to the fluctuation of the mains electricity between 180V to 240V and perform its functions steadily, and overcoming the disadvantages of existing products, such as the proneness to burnout and stop, unstable release of the ion flow, big noise and the difficulty in keeping effective.