To investigate the dynamic changes in the multiple bioactive constituents of Peucedanum praeruptorum Dunn at different harvest times and explore the optimal harvest time for P.praeruptorum.Methods:The total ash content of P.praeruptorum was determined according to the method specified in the 2020 edition of the Pharmacopoeia of the People's Republic of China.The ethanol-soluble extract was measured by cold infusion.After ultrasonic extraction，high-performance liquid chromatography(HPLC) was used to determine the content of coumarin compounds，including umbelliferone，praeruptorin A，praeruptorin B，and praeruptorin E.Volatile components in P.praeruptorum were analyzed using headspace solid-phase microextraction(HS-SPME) combined with gas chromatography-mass spectrometry(GC-MS).Finally，principal component analysis(PCA) was applied for evaluation and ranking to determine the optimal harvest period.Results:The content of multiple bioactive constituents in P.praeruptorum varied dynamically at different harvest times.The total ash content of P.praeruptorum harvested after December was lower，stabilizing around 5.3%.The ethanol-soluble extract reached its peak(42.56%) in mid-December(S4).The total coumarin content was highest on November 17(S1)，then decreased，and rose again to 1.599% in early December(S3).The volatile component content was highest in early December(S3)，reaching 98.3 mg/g.PCA showed that the samples harvested in early December had the highest overall score and were of superior quality.Conclusion:The optimal harvest period for P.praeruptorum produced in Chongqing is from mid to early December.