In order to explore the influence of fissure karst cave on the stability of surrounding rock in the process of tunnel excavation under different water filling conditions，RFPA seepage version numerical software is used to analyze the process of tunnel excavation under different fissure karst cave water filling conditions.The research shows that the existence of water pressure in the fissure karst cave has a significant impact on the stability of surrounding rock.When the water pressure is below 3Mpa，the greater the damage degree of surrounding rock，the faster the damage speed，the more complex the seepage path，and the more serious the water inrush disaster.The existence of water pressure affects the law of energy evolution in the process of tunnel surrounding rock failure.When there is low water pressure（0mpa，1MPa）in the fractured karst cave，the energy released by surrounding rock failure shows the law of evolution of gentle surge gentle surge.When there is a high water pressure（3Mpa）in the fracture cave，the energy released from the surrounding rock failure shows a gentle-surge evolution law.The research results have guiding significance for the prevention and control of water inrush and dangerous rock collapse in the process of tunnel construction in karst area.