Abstract: Traditional estimation method for strength parameters of rock mass does not consider much weather degree.The estimation method of strength parameters of rock mass is put forward by introducing elastic wave velocity ratio λ.Taking hard rock (limestone) and soft rock (mudstone) as examples, the influence of parameter (λ) and normal stress (σ_n) on strength parameters of rock mass is discussed.The results show clearly that elastic wave velocity ratio is an index of weathering zone, based on it and Hoek-Brown strength criteria in this paper, different weathering degree reductive coefficient of shear strength is discussed.The influence of normal stress and elastic wave velocity ratio on shear strength parameters of different weathering degree of rockmass is investigated.The study shows that normal stress and weathering degree of rock mass are main factors influencing strength parameters.The estimation formulas of weathering degree reductive coefficient on limestone and mudstone are suggested by using polynomial fitting method.The study presented in this paper can provide a scientific basis for the stability evaluation of rock mass slope, foundation evaluation and engineering optimization design.