Abstract: The soil rock mixture is a kind of special geological medium formed by soil mixed with irregular rocks,widely distributed in the mountains and had a greater influence to the road and tunnel engineering construction in mountainous area.Because of its particularity,its mechanical property is not easy to find out,which affect on the accurate evaluation,it may cause the waste of engineering cost or improper handling to cause the potential risk of the project.This paper combined with a typical soil rock mixture in TiZi tunnel project of XingYan highway,conducted three groups level shear test in-situ and two groups direct shear test,revealed the mechanical properties of this heterogeneity,inhomogeneous geological medium,by comparing with the in-situ test and laboratory test results,comprehensive analysed and evaluated the Shear strength index of the soil rock mixture,fully emboding the necessity of the in-situ testing work in solving the practical engineering problems.