Objective:To make a comprehensive and quantitative evaluation of the interactions at different ratios between pinellia total alkaloid（PTA） and uncaria total alkaloid（UTA） based on the published data of anticonvulsant and toxicity in combinations.Method: The isobologram and a computer simulation have been used to analyze the interactions of the different levels ED and LD in the combinations.Result: Combinations in the three ratios（PTA∶ UTA = 1∶ 4

1∶ 1

4∶ 1） show a synergistic trend.However

it is difficult to obtain accurate parameters because of the responses（ED

%） at the maximum dose are less than 70%.Combinatin in the ratio of PTA∶ UTA = 4∶ 1 shows an antagonism in toxicity

and at other two ratios（1∶ 4

1∶ 1） the combinations do not provide robust results.In the comprehensive efficacy and toxicity of quantitative parameters

the values of benefit index（BI） in all three ratios are more than 1.The ratio of PTA ∶ UTA = 4 ∶ 1 could reduce toxicity and increase efficacy.Conclusions: The combination at the ratio of PTA ∶ UTA = 4 ∶ 1 shows a significant advantage at the safety and efficacy.This study also provides the performance of methods for design and analysis.