Abstract：he prediction theory and forecast method of tunnel water gushing in karst areas have long been a difficult hydrogeological problem. Based on analyzing karst tunnel water gushing examples in recent years in China，the mechanism of geologic structure for water gushing has been explained through analyzing different karst hydrogeological storage structures；and the existing problems of tunnel geological forecast instruments have been pointed out. In order to find accurate calculation method of water inflow，detailed analysis has been done for the advantages and disadvantages of different calculation methods，as well as its applicable condition. According to different hydrogeological conditions of aquifers，a reasonable and accurate calculation method is put forward. This division system has been further proven in its application of field test.
