Abstract: Linum ustitatissimum Linaceae, known as fax, is rich in lignan in its seeds. As a kind of phytoestrogens , lignan plays an important role in anticancer, antitumor and anti-cardiovascular disease. Therefore, it is significant in conducting the research of extraction. In this experiment, we studied the extraction of SDG from flaxseeds by using the ethanol refluxing extraction （ERE） and ultrasonic acetidin extraction （AE） methods. Extracts were purified by silica gel column. The results show that： the peaking time of SDG is between 2-6 minutes and the recovery rate is 83.3% by using ERE, the peaking time of SDG is between 2-4 minutes and the extraction is incomplete by using AE. Further research needs to be done on ultrasonic time, water bath time and enrichment temperature.