Abstract: According to the mean climatic data of 30 years and contents of alkaloid from 7 wild plant distribution areas in total 21 individuals, the quantitative relationship between climatic factors and contents of alkaloid was researched by stepwise regression analysis, partial correlation analysis and path analysis methods. The results showed that the leading climatic factors that affected contents of alkaloid were annual mean temperature, mean extreme maximum temperature in June, July, August and annual average mean rainfall, which had determined 95.24% of alkaloid content. The main stimulative factor was annual average mean rainfall and the main limited one was mean extreme maximum temperature in August. Annual mean temperature (＜20℃), mean extreme maximum temperature (＜35℃) and annual mean average rainfall (＞1500mm) were the suitable climatic factors for  Sophora tonkinensis. This research could provide theoretical basis for the production of high quality  Sophora tonkinensis, also for optimizing herb production and regulating herb quality.

Key words: Sophora tonkinensis, Content of alkaloid, Climatic factors, Stepwise regression analysis, Path analysis, Decision coefficient