Objective: To study the anti-inflammatory activity of Huanglian Jiedu Tang(HLJDT) and its fractions as well as its material basis. Method: Xylene-induced ear-swelling and capillary permeability experiments were carried out to build the animal model, in order to determine the effective dose of HLJDT and then calculate the dose of each fractions of HLJDT. The animals were randomly divided into the blank group, the model group, the dexamethasone group, the HLJDT group, the HLJDT 50% alcohol-treated supernatant group, the water-treated precipitation group and the 50% alcohol-treated precipitation group, and administrated with drugs according to the traditional way for 3 days. Evans blue(EB) was intravenously injected 60 min later after the last administration, and then the mouse xylene induced inflammation experiment was immediately carried out. The anti-inflammatory effect of HLJDT and its fractions was researched with high performance liquid chromatography(HPLC), and inter-group differences were compared. Result: Compared with the model group, dexamethasone, HLJDT, HLJDT 50% alcohol-treated supernatant and 50% alcohol-treated precipitation could effectively reduce the swelling degree and showed significant difference(P<0.01). The content of EB in the three groups mentioned above decreased to(11.8±1.8),(23.4±3.8),(25.2±3.2) ng·g^-1, the swelling inhibition rates were 26.44%, 29.89%, 19.54%. HLJDT 50% alcohol-treated supernatant showed a more significant effect on anti-inflammatory than 50% alcohol-treated precipitation. Conclusion: HLJDT, HLJDT 50% alcohol-treated supernatant and 50% alcohol-treated precipitation could effectively reduce the swelling degree. On the basis of the result of HPLC, it can be inferred that the flavonoids interacted with alkaloids to reduce the side effect of alkaloids, increase the iridoids and showed a significant anti-inflammatory effect. Therefore, they are the effective anti-inflammatory fractions.