Objective:To characterize nanoparticles which were prepared from biodegradable polymers loaded with resveratrol,and observe the in-vitro anti-tumor effect. Methods:Firstly,mPEG-PCL amphipathic block copolymers were synthesized with ring-opening method. Nanoparticles loaded with resveratrol were then successfully prepared with solvent dispersion method. The morphology,size distribution,encapsulation rate and loading capacity,in-vitro release and in-vitro cytotoxicity against malignant glioma were studied. Results:Nanoparticles prepared with solvent dispersion method proved to be spheric with the size of 71.8±0.2 nm. The highest encapsulation rate was 19.4%. In vitro release experiment revealed the existence of gradual release property. After co-cultured with fluorescein nanospheres,the cells can intake nanospheres through endocytosis. In-vitro cell experiment showed that resveratrol-loaded nanoparticles significantly inhibitied the growth of U251 cells. Especially in low concentrations,resveratrol-loaded nanospheres had stronger cytotoxicity on tumor cells than single free resveratrol. With the increase of drug concentration,resveratrol-loaded nanoparticles had similar cytotoxicity on tumor cells with free resveratrol medicine. Conclusion:Nanoparticles loaded with resveratrol are effective in inhibiting the growth of U251 tumor cells. The study also suggests that they are potentially useful due to their property of gradual release.