To the southwest of Sheshan Mountain and north of Xiaokun Mountain, Tianma Mountain is the first peak of the nine peaks. It is 98.2m above sea level. Its circumference is 2.5km and area is about 120ha.

The mountain has two peaks and looks like a flying horse in the sky, which is the reason for its name (Tianma literally means heavenly horse). Legend has it that Gan Jiang cast swords here in the Spring and Autumn Period (770~476 BC), so it is also called Ganshan Mountain.