A reliability design method of steam turbine blades. is presented. The method considers static stresses, dynamic stresses, endurance strength, safety ratios, vibration frequencies and excition force frequencies of blades as random variables. The strength and vibration design reliability of turbine blades is determined with the help of probabilistic design method. Some reliability calculation formulas are given together with some practical examples. With the reliability design method for steam turbine blades as given in this paper, the design reliability of steam turbian blades can be determined in the design stage. The method may provide some scientific basis for reliability design of steam turbine blades.