Research conclusions : Through the systematic research on the lithological association characteristics of aquifer stratum， hydrodynamic field of karstic water, hydrochemical field and karstic water, this article reached the following conclusion: (1)Karstic water at the tunnel location can be divided into two first level units and seven secondary units.(2)The normal water inflow prediction for the tunnel shall be expressed by Q=24 542 m3/d，and the large water inflow in the rainy season shall be expressed by QL=73626m3/d. (3)The karst water gushing risk in general is medium-high in the carbonate rock section of tunnel.(4)As to the deeply buried carbonate rock of tunnel north，the development degree of the karst and the enrichment degree for underground water are poorer, while in the south the development degree of the karst and the enrichment of the underground are higher, which affect the tunnel water inflow largely. (5)This article can be a directive and exemplificative case for the tunnel survey and design of railway and highway in carbonate rock regions.