In view of low illumination images existing in many application fields, a low illumination image enhancement method based on quantum behaved particle swarm optimization is proposed. The method extracts non-textural regions of low illumination images, and limits the gray level range of non-textural regions to reduce the artifact situation while enhancing the images. A hierarchical probability density function for Histogram Equalization is designed, the improved quantum behaved particle swarm optimization algorithm is applied to search the optimal parameters of hierarchical probability density function. Finally, validation experiments are carried on typical low illumination images, the results indicate that the proposed method not only improves the contrast of images, but also enhances the detail information and visual quality of images.