Cao Jin is rich in hot spring resources, and it is a high-temperature hot spring without heating. Experiments show that if you soak your nails about 15cm in hot springs, the nails will shrink to less than half of their original size on the fifth day, and the nails will become as thin as needles on the second day.

According to historical records, the first generation of Japanese generals Tokugawa Ieyasu, the eighth generation of Japanese generals Tokugawa Yoshinaga, the tenth generation of Japanese generals Tokugawa Kaji and others all sent people to transport the hot springs in Caojin to Edo City in big wooden barrels. Many Japanese celebrities, military commanders and literati have been to Cao Jin Hot Springs. In ancient times, injured soldiers fled to Caojin area and recovered after being treated with spring water without medicine. About a century ago, a prescient German doctor, Dr. Baelz, called Cao Jin Hot Springs "the largest first-class hot spring conservation place in the world". Dr. Baelz is proficient in the latest medical technology in Western Europe. 1876 came to Japan at the invitation of Japan and was called "the father of modern Japanese medical skills". Attracted by Cao Jin's unique spring water quality and mysterious efficacy, he visited and studied hot springs in Cao Jin for many times, and delivered them at the German medical academic conference.

The water quality of indoor and outdoor hot springs in baths is very clean, because strong acidic hot springs have a strong bactericidal effect. Generally speaking, each bath time is no more than 3 minutes; Four times a day, it is said that the best effect can be achieved.