In China, rhubarb (da-huang in Chinese; daiou in Japanese) is processed with liquor. There are two liquors that are commonly used for rhubarb preparations, huangjiu, which contains a small amount of alcohol and baijiu, which contains a large amount of alcohol. Commonly, rhubarb is processed with huangjiu rather than baijiu. However, there is little evidence concerning why huangjiu is used. In this report, we processed liquor-soaked rhubarb using four liquids, distilled water; 16% ethanol; 50% ethanol; and shaoxingjiu, a kind of huangjiu, and compared the amounts of the following principal compounds in the processed rhubarb: sennoside A, sennoside B, aloe-emodin, rhein, emodin, chrysophanol, physcion, lindleyin, isolindleyin, and total tannin. We found that the changes in the amounts of the principal compound in the processed rhubarb mostly depended on the alcohol concentration of the soaking solution. Sennosides content decreased while anthraquinones content increased in a balanced manner when the rhubarb was processed with 16% ethanol or shaoxingjiu. Therefore, rhubarb is processed with liquors that contain a small amount of alcohol as preparing liquor-soaked rhubarb in this manner may decrease its purgative effect and enhance its antibacterial and anti-inflammatory effect.