The yield of ultrasonic assisted extraction of cyanidin-3-O-glucoside,rutin,quercetin and kaempferol in the leaves of Prunus cerasifera were determined by high-performance liquid chromatography (HPLC). And according to the activity of the four substances,the weight calculation formula for the yield of flavonoids in the leaves of P. cerasifera was established. On the basis of single-factor test,Box-Behnken response surface methodology was used to optimize extraction process of flavonoids from P. cerasifera leaves. The leaves of P. cerasifera in different months were treated by the best extraction process,and the flavonoids yield was calculated according to the weight of four substances to determine the best picking month. The results showed that the optimum extraction conditions were as follows:ethanol volume fraction was 63.93%,ratio of liquid to raw material was 25∶1 (mL/g),extraction temperature was 44.08 ℃,and extracted for 41.62 min. And the best picking month was August. The results showed good repeatability and high reliability. The yield of cyanidin-3-O-glucoside changed most obviously over time,and was also significantly related to sunshine conditions. All in all,the study in this paper can provide the beneficial reference for the extraction of related components in the future.