Objective: To analyze the changing regularity of the toxicity of the Mahuang Fuzi Gancaotang through different compatibility methods

and to determine the main factor for reducing its toxicity. Method : Different compatibility methods were used to allocate Ephedre sinica

Aconitum carmichaeli and Glycyrrhiza uralensis . The total alkaloids in all samples were isolated by extraction methods and by different pH value solutions. And ultraviolet spectrometer was used to analyze the content of total alkaloid and ester alkaloid in all compatibility samples. Result : The content of ester alkaloid in compatibility samples was decreased from 46% to 10%

while the content of non-ester alkaloid in compatibility samples was increased from 54% to 89%. Conclusion : E. sinica is similar to G.uralensis in decreasing the toxicity of A.carmichaeli largely and retaining its activity. And the effect of decreasing toxicity is better than other compatibility methods when three kinds of medicines were decocted together at the same time. So

it has important significance to reveal the mechanism of compatibility.