The establishment of tunnel waterproof and drainage principle is the base of determining water treating method, technology and lining design. The Yichang-Wanzhou railway tunnel is with complex geological conditions and various karst cavities, treating of the solution cavities with high water pressure is the emphasis and difficulty. Based on the water rich classification of filling cavities, the waterproof and drainage principle is put up. A universe schedule and a series of protective schedules are put forward in order to control water drainage. For filling cavities that must be dealt with blockage principle, full face curtain grouting and periphery grouting are studied, and a new grouting method "blocking water out of tunnel profile and consolidation in the profile"  is put forward,which helps to accelerate the construction. The structure waterproof and drainage principle is blockage and drainage associating based on actual condition, more waterproof measures are advocated in the principle. The successful experience is helpful for other karst tunnel construction.