The stratum of cave areas is relatively simple, which is the late cretaceous argillaceous siltstone, with lower water content and middle to low density sandstone. The total thickness of rock is more than 100 m, with single layer’s thickness between 0.3 m and 2.0 m. Joints with the direction of N45°∼70°W and N10°∼20°E are developed in the Caverns’ distribution zone. In general, the rock is complete in the Longyou large ancient underground caverns area.