In this paper, the effect of the uncertainties associated with the spatial distribution of rock fractures on the evaluation of loss due to slope failure was discussed. In detail, in order to model the spatial distribution of rock fractures based on stochastic approach, the methodology related to fracture network model was adopted. Finally, the conclusion made it obvious that the results associated with the evaluation of loss are more seriously affected by the spatial distribution of rock fractures, comparing with the effect of other parameters on the results.