The Butterfly Spring is located at the foot of the Yunnong Peak of Cangshan Mountain to the north of Dali. Located some 30 kilometers north of Dali, the spring is clear blue with blister rising slowly from the bottom like pearls. The gnarling boughs of an ancient silk tree stretch over its surface. The Butterfly Spring is actually a pool four meters deep and of the size of 20 square meters. The pool is surrounded with marble railing. Beside the spring, there are various building like the Butterfly Tower, eight-corner towers, six-corner towers, the Crescent Pool, and Yongtie (in praise of butterflies) Stele, etc. Together with plenty of flowers and trees thereabout, these building has made the Butterfly Spring more attractive.

In the fourth lunar month every year, the tree puts out butterfly-shaped flowers, and swarms of butterflies descend on the tree, linking themselves head against tail into numerous colored ribbon-like strings which keep dangling over the pool. And many others just linger over the water and dance. It makes a dazzling scene when beautiful butterflies gathered here every year.

A local legend tells the tale of how it was named long ago. A beautiful Bai maiden named Wengu was in love with a young man named Xialang. A local feudal despot wanted to take her as his concubine. The girl refused; she and her lover drowned themselves together in the pool, and emerged from the pool as a pair of butterflies. Every April when butterflies gather, numerous tourists come to the Butterfly Spring. Some young men and girls of the Bai people also come to the spring to court their beloved ones.

According to the analysis of some botanists, the fantastic spectacle of the Butterfly Spring can be explained as that silk trees and some other balmy trees produce an odor that attracts butterflies from neighboring areas in the end of spring and beginning of summer.