Abstract: In this paper, the sandstone caves of Penglai formation have been taken as the research objects, which is located in Sichuan Yingshan Geological Park of Fangshan area of Northern Sichuan Basin. On the basis of data collection and field investigation, the distribution and types of sandstone caves in the study area were analyzed. Using the method of geomorphology, the caves are measured by wire method, this paper discusses the genesis of different types of sandstone caves in the study area. The results are as follows:The gentle lotus-shaped fold structured fissure and weathering fissure are the tectonic conditions for forming the Fangshan landform and the sandstone caves in this area; the calcareous arkose sandstone with shale in the Penglai formation is the material basis for the development of the caves; the fracture water developed in the sandstone is an important hydrogeological condition for the formation of water tunnel; differential weathering of rock layers is the main reason for the formation of dry caves; karstification, hydration and collapse are the main reasons for the formation of sandstone water tunnels.