The pupil distance of human eyes is a basic parameter which needs to be measured accurately in optometry research and glasses prescription. It is of great application value to realize automatic pupil distance detection. With the help of a Gaussian skin color model, this study proposes a method of pupil location and pupil distance calculation based on gray integral projection and Hough circle transform. Firstly, the image is subjected to the preprocessing of illumination compensation by the adaptive brightness correction method of a two-dimensional gamma function. On this basis, the face area is extracted by using a skin color probability model. Then, the gray integral projection method is used to extract the eye area by selecting an appropriate threshold. After morphological image processing, the Canny edge detection operator is utilized to detect the pupil edge. Finally, the pupil location is carried out by Hough circle transform, and the center distance is calculated. The results show that the algorithm has a fast pupil location speed and can realize the automatic pupil distance measurement more accurately, which lays the foundation for the research on intelligent technologies of pupil distance measurement.