Suzhou Xishan area is located in the southeast of the Yangtze platform fold belt under the Yangtze paraplatform, with well-developed geological structures, the most famous of which is the Piao Sha Feng nappe structure. Where the limestone strata in the Late Carboniferous are exposed, it is characterized by the development of karst landform. The mountain is rugged and looks like a flock of sheep, forming a curved or straight sky and various stone forests at the crack development place. Due to the long-term effect of groundwater and surface water, karst landforms are very developed. Linwu karst cave is controlled by two groups of faults in the northeast and northwest, and is formed by long-term dissolution of groundwater. It is still under development, and it is a very young cave. At the same time, due to the nearly horizontal occurrence of rock strata, under the action of gravity, rock strata collapse to form "gravitational relics" in caves such as flat-topped stone graben, which are straight or curved, long or short, with different postures. Taihu stone, common in gardens, was first discovered in the western hills of Taihu Lake. The stone surface is concave and convex, connected by vortex holes, white and round, with five characteristics: "thin, leaking, transparent, wrinkled and strange" Up to now, there are different opinions on the causes of Taihu Lake, including "lagoon theory", "tectonic subsidence theory", "water accumulation theory", "wind waterfall erosion theory" and "meteorite impact theory". Among them, the viewpoint of exhausting, blocking and accumulating water into lakes is generally accepted by most earth scientists. According to research, Taihu Lake was last formed 2000 ~ 2500 years ago.