There are two types of decoction of Smilax glabra due to its reddish brown or off-white colored cross section. These two kinds of decoction were found that they have large difference in anti-inflammatory effects and chemical constituents in the preliminary experiments. Comparing and analyzing the content of total tannin in these two kinds of decoction of S. glabra from 28 areas by UV-Vis spectrophotometry were first used to provide some experimental and theoretical development and utilization of this medicinal resource and quality control. Also, the sample recovery test required in Chinese Pharmacopoeia was improved by adding tannic acid instead of gallic acid to samples.