Also known as Zhuoyue Spring, the spring is on the southern slope of Huzhu Pagoda in Tianma Mountain Park. According to the legend, Sage of Tea Lu Yu born in the Tang Dynasty(AD 618-907) even visited Tianmashan.

He found spring water gushing out from the bottom of a stone pond. People of a later generation found a stone in the pond. On the stone, "No.4 Spring in the World" was inscribed. It was proved that the characters were written by Lu Yu. Lu Yu not only studied the art of tea and tea sets but also observed the spring water used for making tea in regions south of the Yangtze River.

He rated the springs based on water quality: "Zhongleng Spring" in Zhenjiang is No 1 spring in China, followed by "Huishan Spring" in Wuxi, "Jianchi Spring" in Suzhou, and "Zhuoyue Spring" in Tianma Mountain. Here the spring water is cool and sweet. The Shanghai Longjing tea brewed with this water is a top-grade drink. Recently, "No 4 Spring in China" has become discontinuous. On rainy days, water will gurgle out from the stone cracks.