To determine the change pattern of alkaline and acid components of Dahuang and Fuzi in different combinations.The contents of anthraquinones and aconite alkaloids were determined by HPLC in samples of Dahuang extracts, Fuzi extracts, Dahuang and Fuzi pair medicines extracts, and extracts of whole recipe.As for Dahuang, the contents of anthraquinones were decreased with changes of combination: higher contents were in decoctions of Dahuang alone, lower contents were in decoctions of pair medicines, and the lowest contents were in decoctions of whole recipe. As for Fuzi, monoester aconite alkaloids could be detected in water extracts, and both biester and monoester aconite alkaloids could be detected in ethanol extracts. The contents of aconite alkaloids were decreased with changes of combinations: from Fuzi alone to pair medicines, and to whole recipe. The change pattern was more apparent when extracted in water decoction.The contents of alkaline and acid components are changed with different extract methods and different combinations.