To establish a new method for frozen section of Angelicae pubescens root，and study the histochemical localization and conduct quantitative analysis of coumarins in A.pubescens root at different growth stages by fluorescence imaging，to clarify the tissue distribution and dynamic accumulation pattern of active component coumarins in A.pubescens root.Methods:With A.pubescens root at different growth stage used as the research material，the effects of different protective agents and section thickness on the optimal section of A.pubescens root were investigated，and the optimum conditions for sections were established.In addition，microscopic imaging technology was used for statistical analysis of secreted tissues in different parts，and fluorescence imaging was combined to measure the fluorescence intensity of the parts where coumarins were concentrated.The relative quantitative analysis of coumarins in A.pubescens root at different growth stages was carried out by fluorescence intensity，and their dynamic change pattern was analyzed.Results:The optimal section effect of A.pubescens root was obtained when the section thickness was 25 μm and under the treatment with 15% glycerol protectant.Histochemical localization showed that coumarins were mainly distributed in the secretory cavity and secretory tract of the phloem.The overall change trend of coumarins in A.pubescens root at different growth stages presented a S-shaped increase，with obvious content change in August and October and the maximum content in October.Conclusion:The frozen sectioning and fluorescence imaging of A.pubescens root were established for the first time，and the generation，distribution and accumulation of coumarins were studied.It was found that coumarins were mainly distributed in the secretory cavity of the phloem.The dynamic change trend of coumarins in A.pubescens root at different growth stages showed a S-shaped increase，and the accumulation of coumarins reached the maximum in October.This paper provides a new idea for expanding the analysis of traditional Chinese medicine.