Research method: Ordinary concrete-water glass two-shot grouting and extra fine concrete-water glass two-shot grouting are adopted in construction of the pilot tunnel under karst cave 2. By this way, it is difficult to pass through one cave. Following it, after the level pilot tunnel encounters karst cave, two-shot grouting is adopted, but the result is not good. To such situation, the grouting materials are adjusted and ordinary concrete one-shot grouting and extra fine concrete one-shot grouting are introduced to form group grouting materials. The group grouting materials increase the grouting effects for level pilot tunnel. But after it rains on earth surface, the grouting solidification is broden down by high-pressure water and cause failure of grouting. Through summing up the experiences and learning lessons, TGRM grouting and HSC grouting are introduced to form a complete set of system and selected model with six kinds of grouting materials.