Liquid crystal achromatic polarization rotator is an optical element which can change the state of incident polarized light. In order to realize the transformation of polarized light in orthogonal direction and have good achromatic performance in wide band without moving polarizing components, an achromatic polarization rotator composed of three low-twisted nematic liquid crystal cells is proposed to control the distribution of liquid crystal molecules by applying voltage to control the state of the polarized light. TechWiz LCD 1D software is used for simulation. In the case of no voltage and parallel polarizer, the light leakage rate of the chromatic polarization rotator in the range of 450~650 nm is less than 0.01, and the light leakage rate in the range of visible light is less than 45%, which is lower than that of the rotator composed of a traditional twisted nematic liquid crystal cell. When the voltage is applied, the transmittance can reach more than 97.9%, and when the thickness of the liquid crystal cell changes between 2.2~2.5 μm, the achromatic characteristic is almost unaffected. This structure of achromatic polarization rotator has high ratio, good achromatic performance and fast response time which meets the requirements of polarization rotator devices.