岩溶泉即地下岩溶水的天然出露点，是含水层或含水通道与地面相交处所产生的地下水涌出地表的现象。内勉屯岩溶泉形似眼睛，长约20m，宽约5m，深约30m。水质清澈，丰水期时泉水上涌。

Karst spring is a natural outcrop of underground karst water. Underground water surges upwards under relatively high pressure at the intersection of aquifers or water channels and the ground. The Neimian village karst spring is shaped like an eye, about 20m long, 5m wide and 30m deep. The water is clear, and the spring water surges during the wet seasons.