Abstract : Research purposes ： In the process of railway tunnel construction， tunnel surrounding rock grade is often changed when its geological condition is not consistent with corresponding design. In practice， applying seismic compressional velocity on the classification will cause some problems. At present，tunnel surrounding rock grade is still qualitative. Due to tunnel surrounding rock grade related to the economic interests of all participation of the tunnel construction，construction progress and safety， participation are highly concerned about the tunnel surrounding rock grade alteration. Currently，a standard method of predicting the tunnel geological is called seismic reflection method (TSP) . The data collected from the metliod includes various physical and mechanical parameters and spatial variation of the surrounding rocks. Therefore，the TSP method can solve the problems that are in the quantitative tunnel surrounding rock grade by the predicted data. Research conclusions:(1) By using the TSP prediction data，the basic index of tunnel surrounding rock classification based on lithology and dynamic Youngs modulus，the correction index of the tunnel surrounding rock classification based on Poissons ratio and its variation，combined with reflector interface density，the railway tunnel surrounding rock can be graded quantitatively in Table 1 and its instructions in the paper. (2) In theory，this classification is consistent with the railway tunnel surrounding rock classification system. ( 3 ) The quantitative index of the tunnel surrounding rock classification proposed in this paper still need to be constantly revised in practice.