Abstract: The determination of the mechanical parameters of surrounding rock mass is a difficult and key issue in tunnel engineering stability evaluation and numerical calculation. The geological strength index(GSI) is just a classification system for solving this issue. The quantitative method of GSI and Hoek-Brown criterion that estimates the surrounding rock mechanical parameters is introduced. Based on quantitative disturbance index D and absolute weathering index AWI,the surrounding rock mechanical parameters of a highway tunnel are evaluated. Under the condition of lacking in situ-test and plenty of sample data,this simple and practical method can accurately reflect the mechanical properties of jointed surrounding rock mass and given for reference of similar projects.