Objective : The present study aimed to evaluate the change of the content of 7 active components in decoctions produced by various proportional pairs of Coptis chinensis Franch and Scutellaria baicalensis Georgi in ‘Mixed decoction (MD)’ and ‘Single decoction mixture (SDM)’. Methods: The samples of MDs were prepared by decocting C. chinensis: S. baicalensis with the ratios of 10 g:10 g, 10 g:20 g, and 20 g:10 g. Those of SDMs were prepared by blending each single decoction from C. chinensis and S. Baicalensis with the ratios of 1:1, 1:2, and 2:1. The samples were evaluated by high-performance liquid chromatography with statistical analyses. Results: The analytical methods, which were optimized and validated, were reliably applied to present research. The content of all components in both MDs and SDMs at C. chinensis: S. baicalensis = 1:1 ratio were reduced compared with single herb decoction. The components from each compositional herb in MDs were proportionally increased with the ratio of original herb increased, but inversely proportional to paired herb. The contents of components in MDs were significantly lower than those in SDMs at all ratios, except for high content of baicalin at C. chinensis: S. baicalensis = 2:1. Conclusion: It was concluded that MDs and SDMs as well as the proportions of herbs could affect the contents of the components from original herbal medicines. These results provide the information for the quality control of herbal medicine combined C. chinensis with S. baicalensis.