The method for calculating random-fuzzy reliability in limit equilibrium analysis of stability of the slope with divcular potential sliding surface is presented.The corresponding calculation formulas are deduced by combining fuzzy mathematics with reliability theory.The random-fuzzy reliability of the slope engineering is expressed by the fuzzy(event)-exact(probability) index in the suggested method.Both the objective attributes of rock soil mass and the quantitative evaluation of slope engineering stability are considered at the same time.The calculation formulas in the method are determinate and convenient for use.