The invention discloses a point spot detection and background noise feature estimation method for a point source Hartmann wavefront sensor. When the method is used for point spot detection and background noise estimation on a certain sub aperture, as for each pixel in the sub aperture, the difference between the gray variance in a neighborhood and the gray variance outside the neighborhood is calculated; the position of the pixel corresponding to the maximum difference in all pixels is then obtained, the neighborhood of the pixel serves as the detected point spot area, and the gray mean value and the gray variance in a non neighborhood of the pixel serve as the mean value and the variance for noise estimation. The method has a simple and stable process, and the realization is easy; compared with the existing background noise estimation method, the method of the invention can estimate the statistical characteristics of the background noise more accurately, the point spot area can be detected at the same time, and thus, the point source Hartmann wavefront detection stability and the precision are further enhanced.