天宝山穿洞位于天宝山中部，洞口正面近似正方形，边长约20m。穿洞所在岩体为碳酸盐岩，由最初的地溶洞经进一步崩塌溶蚀及地壳抬升露出地表形成。穿洞顶部平坦，底部倾斜，北高南低。北侧洞口可见石钟乳，钟乳石表现出向光性；洞底有崩塌堆积体，为洞壁及洞顶发生崩塌所致。洞内生长有植被。天宝山下有一段伏流，正面可见伏流的入水口。 The Tianbaoshan karst cave is located in the center of the mountain. the cave mouth from the front is approximately square, the side of which is about 20 m long. The lithology of this karst cave is carbonate rock, formed by further corrosion and collapse of the earlier karst caves, and later crust uplift. With the north higher than the south, the top of the cave is flat and the bottom inclines. There are stalactites in the north side of the cave mouth, which grow toward the light. There are collapse deposits at the bottom of the cave, causing by the collapse of the cave wall and the cave roof.  There also grows vegetation in the cave. And there is a part of underground river in Tianbaoshan, from the front side, its water inlet of which can be seen.