Objective:This study aimed to improve the recrystallization yield and purity of flavonoid.Methods:Taking the crude flavonoids from pomelo peel extracted by ultrasonic-assisted ethanol extraction as raw materials, the process parameters of ethanol recrystallization and purification of flavonoids were optimized by response surface methodology.Results:The main factors affecting the recrystallization yield of flavonoids were ethanol concentration, crystallization time, pH value, and the interaction between ethanol concentration and pH value, among which, the ethanol concentration affacted most significantly.Conclusion: The optimal recrystallization conditions of flavonoids were as follows: ethanol volume fraction of 24%, liquid-solid ratio of 10∶1 (mL/g), pH 3.75, crystallization temperature of 4 ℃, and crystallization time of 24 h. The crystallization yield of flavonoids was 8.76%, and the main crystallization product was naringin with a purity of 83.38%.