The invention discloses a stereological method for measuring alloy residual second phase nearest neighbor distance distribution. The stereological method comprises the following steps of sample preparation, image photographing, image preprocessing, second phase boundary extraction, nearest neighbor second phase recognition, second phase nearest neighbor distance calculation and nearest neighbor distance statistics. A backscattered electron image is used as an analysis object so that sample preparation time is saved and the accuracy of subsequent measurement work is enhanced. According to the method, the calculated distribution parameters are more visual in definition, accurate and clear in physical meaning and more suitable for describing the distribution characteristics of the second phase or impurities having certain randomness in shape and orientation. The distribution parameters of the residual second phase are automatically calculated by using an image processing method so that labor cost is reduced, the accuracy of the measurement result is guaranteed and large amount of work time is saved. The method has general research and application value. The method is also suitable for mixed phase element distribution and mixed phase characteristic analysis of other metal and nonmetal material with different bases.