Abstract: Optimization of extraction of flavonoids from Lycium barbarum L. var. auranticarpum K.F.Ching,and comparing antioxidant activity in vitro of three Lycium barbarum L. var. auranticarpum K.F.Ching. In this paper,using the response surface experiment design to optimize extraction of flavonoids with 'Ningnongqi 5’ as raw material,measure and analysis of the antioxidant activity of flavonoids extracts of three representative Lycium barbarum L. var. auranticarpum K.F.Ching,compared with Lycium barbarum L. and Lycium ruthenicum Murray simultaneously. Results showed that the temperature of water bath was the main factors influencing the flavonoids extraction,the best parameter of flavonoids extraction was 70% ethanol concentration,volume ratio of 40 times,water bath temperature 70 ℃ with 90 min,the flavonoids content was(175.21±1.69) μg/g.Antioxidant activity analysis in vitro indicated that 'Ningnongqi 5’ has strong clearance ability of ABTS and DPPH,27.71%±0.66% and 15.3%±0.84% respectively,which was higer than Lycium barbarum L.(22.72±0.50%,12.55±1.20%),but not as good as Lycium ruthenicum Murray(33.33%±0.49%,81.61%±1.25%). Through correlation analysis,total flavonoids content had a significant positive correlation with ABTS clearance rate,extremely significant positive correlation with DPPH clearance rate and FRAP value. The total phenol content had a significant positive correlation with ABTS clearance rate and DPPH clearance,which showed that flavonoids were main ingredients of Lycium barbarum L. var. auranticarpum K. F. Ching exhibiting antioxidant activity.