Two peaks stand opposite each other, one wide and the other narrow, one large and the other small, forming the shape of a gate — hence the name Guanmen Mountain, meaning "Gate Mountain".
There are three mountain passes here.
The North Gate faces Xiaoshi Town. The twin peaks face one another, connected by an arch bridge in the middle.
The South Gate sits on the mountain ridge leading to Tanggou. The highway cuts right through the pass, creating a precipitous passage.
The Middle Gate is located along the river in the deep valley. Two steep cliffs clamp the river, leaving a channel merely more than 20 metres wide. The natural rock walls serve as perfect gateposts for building a reservoir.