In Chinese, "Caishi" (菜市) means farmers market. This place used to be a bustling farmers market in Song daynasty. You'll see the wall engravings under Caishi bridge which depict the past prosperous time.
** something you should know before geocaching in China **
The google map in official geocaching app has a large off by about over 500 meters in China. But the google satellite view in third party app such as c:geo match. The OSM or your GPS is also reliable.