The images captured in a hazy environment are always prone to blurring. To restore the hazy images, a transmission function estimation algorithm based on the RGB color space ellipsoid model is proposed. First, the gray values of pixels in a neighborhood of a hazy image were mapped to RGB color space, and the aggregation state of pixel gray values were fitted by an ellipsoid model. Furthermore, all vectors in the ellipsoid were projected onto the atmospheric light vector to estimate the transmission function for each pixel. Finally, the transmission function is optimized and combined with atmospheric light vector estimation to restore the hazy images. Experimental results indicate that the proposed transmission function estimation algorithm, which is based on the RGB color space ellipsoid model, can effectively restore the hazy images.