RESUMO
<p><b>OBJECTIVE</b>To study the dynamic accumulation regulation of dry substance and four coumarin constituents in root of Peucedanum praeruptorum, so to provide the basis for optimal harvest time.</p><p><b>METHOD</b>Roots of P. praeruptorum were collected periodically. The dry weight of the roots was measured and the content of four coumarins was determined by HPLC method.</p><p><b>RESULT</b>The dry substance accumulation of the root reached the maximum amount and the coumarin contents maintain stability at the end of the vegetative growth period. The coumarins of roots decline significantly in the reproductive growth period.</p><p><b>CONCLUSION</b>The most optimum collecting time of root of P. praeruptorum cultivated in Ningguo county in Anhui province should be from December to next February.</p>