Abstract: AimTo explore the combination principle about aconite roots from the chemical point of view. MethodsAnalyzing and comparing the nordeterpenoid alkaloids in the crude aconite roots, the decoction of crude aconite roots and aconite roots with some other Chinese traditional herbs by electrospray ionization trap tandem mass spectrometry. Detecting the pH value of the decoction of crude aconite roots and of some other Chinese traditional herbs; studying the influence of acidity to the hydrolysis of standard sample of mesaconitine. ResultsMost of diester-diterpenoid alkaloids in the decoction of aconite roots and the decoction of aconite roots with liquorice roots are hydrolyzed, and the hydrolysis of alkaloids are inhibited in the decoction of aconite roots with Pinellia tuber or Schisandra. The acidity of the decoction of aconite roots or liquorice is lower than the decoction of Pinellia tuber or Schisandra; standard sample of mesaconitine can not be hydrolyzed in acid water. ConclusionAcidity is a key factor to influence the hydrolysis of diester-diterpenoid alkaloids, and the hydrolysis of alkaloids are inhibited in high acidity, which lead to the high toxicity of the decoction containing aconite roots.