位于东平河西岸，穿洞近似圆形，高约15m，宽约10m，绝对海拔约390m。由于周围山体的遮挡，随着远观角度的不同，穿洞则呈现如同月亮阴晴圆缺的形状，因而得名“月亮山穿洞”。 Moon mountain karst cave is located in west coast of Dongping river. This cave is near round, the hole of which is 15 m high,10 m wide, with a sea level of 390m. Shaded from its surrounding mountains, the caves appears to be different shapes, with different view angles, the same as the changes of the moon as it waxes and wanes, so hence the name Moon mountain karst cave.