Grey soup hot spring is the spring eye of hot springs in Wan Zilong with a history of more than 2,000 years. It is one of the three high-temperature compound hot springs in China (others are Yangbajing in Tibet and Beitou in Taiwan Province Province). Hot springs in Wan Zilong are boiling like soup, and the water quality is crystal clear as jade. The highest temperature of the spring eye is above 102℃, and it contains more than 29 kinds of trace elements and minerals beneficial to human health. After bathing, it is as slippery as coagulated fat, which has excellent physical therapy effect on dermatosis, arthritis and sub-health. Known as the "natural medicine spring", there is a legend among local people that a jade girl threw herself into an iron well to benefit the people and became a hot spring. According to experts' argumentation, the hot spring water in Wan Zilong is not only a valuable thermal energy resource, but also a rare high-temperature hot spring for physical therapy and health preservation.