RESUMEN
Objective To determine the appropriate collecting -time of Exocarpium citri grandis,the chemical compo-sition in Exocarpium citri grandis in different fruit -ages was compare d and analyzed.Methods Contents of naringein and bergapten were compared by TLC an d the total dihydroflavones in Exocarpium citri grandis was determined by spec-trophotometmic analysis with detection wavelength at 384nm.Results With the increase of fruit -age,the c ontents of naringein and total dihydroflavones in Exocarpium citri grandis decreased and the content of bergapt en increased.Con-clusion Fruit -age has an obviously effect on the chemical composition in Exocarpium citri grandis and collecting -time can influence the quality of medicin e materials.Further studies of Exocarpium citri grandis should be combined pharma-codynamics for fixing collecting -t ime.