[en] Jiji sub-area is one of the candidates in Beishan area, Gansu province-the preselected area for Chinese high-level radioactive waste repository. 13012 joints data is obtained by comprehensive joint survey method in Jiji quarry. According to the two faults, Jiji quarry is roughly divided into three statistical homogeneities and two region which is influenced by the two faults. Based on the theory of circular sampling window, a computer program is developed and it is used to analyze the diversity of the mean trace length and trace midpoint density in the both side of the faults. So the boundary of the statistical homogeneities is determined and the mean trace length and trace midpoint density of each statistical homogeneity is obtained. The predominant joint cluster of each statistical homogeneity is obtained by rose diagram and equal-area upper hemisphere projection method. The distribution of joint's orientation can be effectively fitted by normal function and the joint dip angles are mostly steep. The joint space of each joint set is calculated and it can be effectively fitted by negative exponential function. According to Suggested Methods for Quantitative Description of Discontinuities in Rock Mass (ISRM,1980), the joint space of each statistical homogeneity is wide spacing. The quantitative parameter of rock mass joint characteristic is obtained and it is essential for further studying the mechanics and seepage characteristics of rock mass. (authors)