The invention discloses a method for judging the focal reconstruction distance of a digital hologram based on the intensity variance of a reconstruction image, belonging to a method for judging an automatic numerical value of the reconstruction distance of the digital hologram in the technical field of precise optical measurement. According to the invention, the clear degree of the reconstruction image is judged and analyzed by utilizing the ratio of the intensity variance of the reconstruction image to the average value of the intensity of the reconstruction image; a clear reconstruction intensity image and the corresponding accurate reconstruction distance of the digital hologram are found out; by means of the method, judgement of the automatic numerical value of the reconstruction distance of the digital hologram can be realized; and the measurement precision and the measurement efficiency of the reconstruction distance are increased.