Objective:To prepare 7-hydroxyethyl chrysin(7-HEC)loaded poly(lactic-co-glycolic acid)(PLGA)nanoparticles and to detect the in vitro release.Methods:The 7-HEC/PLGA nanoparticles were prepared by emulsification solvent volatilization method.The particle size,polydispersity index(PDI),encapsulation rate,drug loading and zeta potential were measured.The prescription was optimized by single factor investigation combined with Box-Behnken response surface method.Mannitol was used as protectant to prepare lyophilized powder,and the optimal formulation was characterized and studied for the in vitro release.Results:The optimal formulation of 7-HEC/PLGA nanoparticles was as follows:drug loading ratio of 2.12∶20,oil-water volume ratio of 1∶14.7,and 2.72%soybean phospholipid as emulsifier.With the optimal formulation,the average particle size of 7-HEC/PLGA nanoparticles was(240.28±0.96)nm,the PDI was 0.25±0.69,the encapsulation rate was(75.74±0.80)%,the drug loading capacity was(6.98±0.83)%,and the potentiostatic potential was(-18.17±0.17)mV.The cumulative in vitro release reached more than 50%within 48 h.Conclusions:The optimized formulation is stable and easy to operate.The prepared 7-HEC/PLGA nanoparticles have uniform particle size,high encapsulation rate and significantly higher dissolution rate than 7-HEC.