Abstract: The Qaidam Chinese Wolfberries were used as the raw material in carotenoid extracting. In order to improve extraction content,the method of ultrasonic- assisted organic solvent extraction was adopted. Based on the single factor experiments,solid- liquid ratio,the ratio of the extraction solvent and the extraction time were optimized by Box- Behnken Design. The inhibitory rate of DPPH scavenging activity was analyzed antioxidant activity of carotenoid.Under optimal extraction conditions,the contents of carotenoid in Qaidam Chinese Wolfberry from different producing areas and different picking period were determined.By the optimizing of response surface method,the optimalizing technique was obtained,which was that the extraction solvent was petroleum ether and ethanol mixtures( v / v = 2.6 ∶ 1),the solid- liquid ratio was 1 ∶ 60( g / m L),extraction time and extraction times were41 min and 1,respectively. The content of carotenoid in Qaidam Chinese wolfberry was 321.52 mg /100 g under optimized conditions.The half maximal inhibiting concentration( IC50) of DPPH scavenging activity of carotenoid was34.09 μg / m L. There were statistically significant differences in carotenoid content in Qaidam Chinese Wolfberry compared with different producing areas and different picking period( p < 0.05).