Abstract: Through analyzing the Maoba synclining karst cave exposed by the Yuanliangshan tunnel and the distinct distribution of karst in superficial layers, the authors identified characteristics of deep karst development and the contributing factors. The results indicated that the karst water moves downwards into the deep layers under favorable hydraulic gradients or pressure heads, especially under influence of water gravity. As a result, the karst is developed at depth with erosion of water. At the same time, a karst zone is developed between the thick confining bed and the base of the drainage. In the same geological formation, the similarity in distribution is observed for both shallow and deep layers.