Abstract: To establish a HPLC method to determine the content of aucubin in Eucomm ia ulm oides seeds, to searchfor the formation and accumulation of aucubin in Eucomm ia ulm oides seeds, and to p rovide foundation for thesuitable harvest season of aucubin in Eucomm ia ulm oides seeds, the Hypersil GLOD2C18 column ( 250 mm ×4. 6mm, 5μm)with temperature at 25 ℃was used. The mobile phase wasmethanol-water (8∶92), at a flow rate of 1. 0mL·min-1, and the detective wavelength was 206 nm. The results indicated that the method of HPLC was efficient, and the average recovery of the aucubin in Eucomm ia ulm oides seeds was 98. 61%, RSD = 1. 14% ( n = 6). Thedetermination of aucubin was gradually raised with the seed growth, while the formation and accumulation from June25 th to Sep tember 5 th increased slowly, and the determination of aucubin from Sep tember 5 th to 25 th raisedquickily, and then kep t relatively stable. Considering the extraction and utilization of aucubin, the date fromSep tember 25 th to October 25 th was the most suitable period for collecting Eucomm ia ulm oides seeds.