Abstract: Three dimensional network modeling technique for random discontinuities of rock mass is a significant method to evaluate the structure of rock mass， nevertheless， the effect of fracture width on rock mass stability is not considered in the model. Based on the in situ investigation of discontinuity traces in sampling window， the fracture widths of sampling window is analyzed by the method of combining chisquare test and K-S test， and finally， the optimum probability distribution types were chosen. The statistic analysis results showed that the main distribution type of fracture widths of Liaoyang Shimen dinas rock slope is gamma distribution， most fracture widths are under 10mm， and type of tectonic stress affected the distribution parameters of fracture widths greatly. This result can provide theoretical basis for 3D network modeling of the fracture width.

Key words: 3D network, fracture width, stochastic mathematics, chisquare test, K-S test