Abstract: Flavonoids were extracted from the buds of Sophora japonica L. by different methods, such as alkali dissolution of acid sedimentation, ethanol reflux, and ultrasonic-assisted methods. The extraction conditions, including the pH of the base and the kind of stabilizer were researched as well. Furthermore, with rutin as a control, thermal characteristics of flavonoids from the buds of Sophora japonica L. were determined Via the TG-DTG curves. The results showed that every sample had different mass loss, curve shape, and peak location related to different extraction technology. The TG-DTG characteristics of the products extracted by alkali dissolution of acid sedimentation with the extract adjusted to pH=9 and borax as the stabilizer were similar to that of standard rutin. Meanwhile, the yield and purity of the products extracted by the above optimum extraction technology were higher than others. Therefore, the thermal analysis fingerprint could serve as a tool for quality control of flavonoids from the buds of Sophora japonica L.