Abstract: Objective To study the "risk-benefit threshold" of toxic herbs and provide objective reference for their application. Method Taking Radix aconiti Sinensis and Radix aconiti Kusneziffii (Chuanwu and Caowu) with acrid, hot and toxic properties as an example, a benefit-risk assessment (BRA) model was established by integrating multi criteria decision-making, meta analysis and entropy weight method. The "threshold" exploration based on the evaluation results was carried out, and the key factors affecting the expression of efficacy and toxicity in toxicity were found and the range of interval was quantified. Result A relatively stable BRA model was established to evaluate the effect of different "threshold" conditions and intervals on the benefit risk expression of sample drugs based on the included randomized controlled trials. Conclusion "risk- benefit threshold" could provide objective basis for the rational use of toxic herbs, and also could carry out targeted early warning and prevention.

Key words: risk-benefit, threshold, herbs with acrid, hot and toxic properties, Radix Aconiti Sinensis, Radix Aconiti Kusneziffii