Abstract: Saponins were extracted from Gleditsia triacanthos L. shell by using anhydrous ethanol.The component analysis, saponin yield, sugar content and composition on saponins and surface activity of saponins in G. triacanthos shell at different growth time were systematically studied. The results showed that the saponin yield increased with the growth time increasing. The maximum mass fraction of saponin reached 14.21% at 25 weeks after flowering. The HPLC method indicated that the sugar chains of G. triacanthos saponins were mainly composed of glucose, xylose, arabinose and rhamnose. The content of hydrophilic sugar groups on saponin decreased first and then increased with the growth time increasing, and reached the lowest at 21 weeks.The surface activity of saponins was affected by the content of hydrophilic sugar groups. Meanwhile, the critical micelle concentration of saponins in G. triacanthos shell also decreased first and then increased with the growth time increasing. The critical micelle concentration was the lowest(0.07 g/L) at 21 weeks, and the surface tension was 44.57 mN/m. G. triacanthos shell saponins performed the best surface activity at 21 weeks, which were the most suitable for the production of surfactants. The results of FT-IR spectra confirmed that the extracted and purified saponins from G. triacanthos shell had the basic characteristic peaks of saponins.