AIM: The mechanism of extracting flavoinoids from Ginkgo biloba leaves by microwave prtreatment was studied systematically. METHODS: The dired leaves were used as the crude drug, the effect of the operation parameters during the extraction on the extraction result was analyzed with monofactor experiment, and spectrophotometer was used to observe the structure of the cells. RESULTS: After the microwave pretreatment, the structure of the leaves cell was destroyed and the effective composite was desorbed completely. The following extraction rate was 4 times higher that of traditional extraction, the yield and the purity were better than the ethanol extraction. CONCLUSION: The short extraction time, higher yield of effective composite, higher usage rate of the microwave, the method is worthy to be used. W