Abstract: The study on structural homogeneity dividing has attracted attention in geotechnical engineering. The occurrence (dip and dip angle), trace length, width and shape of discontinuity are fully considered by means of stochastic mathematics, and the structural homogeneity of fractured rock mass is divided based on the contingency table chi-square tests which can validate the difference between samples. The dividing method is more accurate because it takes more parameters, which reflect the feature of rock mass. The structural homogeneity areas are 18~90 m and 108~144 m, respectively . However, there are some defects which neglect detailed difference of the compared samples. Therefore, the spatial effect of the structural homogeneity dividing is introduced. Because the distribution of the rock mass discontinuities is heterogeneous, the dividing of the structural homogeneity varies obviously with change of the study space. The spatial effect of the structural homogeneity dividing is proved to exist through changing the space of the compared samples, and the structural homogeneity is divided based on the spatial effect. The structural homogeneity areas considering the spatial effect are 18~57 m and 108~144 m, respectively.