Sour plum juice existed in China a long time ago, but it is called Sour Plum Soup in some places. "Tu Gong Mei Jian" contained in ancient books is the oldest sour plum juice. "Plum-stewed water" mentioned in "Old Wulin Story" in the Southern Song Dynasty is also a refreshing drink similar to sour plum soup. Today, the sour plum soup we drink is a summer-cooling and thirst-quenching drink made for the emperor in the imperial dining room of the Qing Dynasty, which was later spread to the people. It was 15 years earlier than the soda introduced into China from Western Europe. Sour plum juice is a traditional summer drink in old Beijing. In the hot season, most people will buy ebony to cook it by themselves (or use red bayberry instead of ebony), put some sugar in it to remove the acid, and drink it after cooling.