Abstract: Objective: To improve the water solubility of Kudinoside D. Methods: Using atmospheric column chromatography, semi-preparative high performance liquid chromatography and other means to separate and purify saponins from Ilex kudingcha C.J.Tseng, the compound Kudinoside D was obtained. Using polyglutamic acid (γ-PGA) and L-phenylalanine ethyl ester (L-PAE) as raw materials, Kudinoside D nanoparticles were prepared by precipitation method and dialysis method respectively. The physical and chemical properties of nanoparticles were characterized by transmission electron microscopy and dynamic nanoparticle size analyzer, and their in vitro drug release characteristics were investigated by dialysis. Results: Compared with the precipitation method, the encapsulation efficiency and drug loading of Kudinoside D nanoparticles prepared by the dialysis method were increased by 1.5 and 4.5 times, respectively, the encapsulation rate reached 65.46%, and the drug loading reached 13.24%. Kudinoside D nanoparticles had a regular spherical shape with an average particle size of (75±25) nm and a Zeta potential of 33.7. Conclusion: In vitro drug release experiments show that Kudinoside D nanoparticles can significantly improve the water solubility of the drug and have a good sustained release effect in vitro.