To find a component with the strongest anti-endotoxin effect from the four components (F021 , F022, F023, and F024 ) of chloroform extract (F02) of Radix Isatidis, the protective effects of the five components on endotoxin-challenged mice and their effects on the production of TNFα and IL-6 by macrophages from the endotoxin-challenged mice were compared. It was found that the five components all had protective effects on endotoxin-challenged mice in terms of mortality. The mortalities of the mice challenged by 2.42 mg/kg endotoxin were 30 %, 50 %, 20 %, 50 % and 60 %after treatment with F02, E021 , F022, F023, and F024. The 5 components all had inhibitory effects on the production of TNFα and IL-6 by macrophages from the mice. At a concentration of LPS of 50 ng/mL, the inhibitory rates of F02 , F021 1, F022 , F023 , and F024 for the production of TNFα and IL-6were 76.54 %, 30.86 %, 78. 60 %, 36.63 %, 2.06 % and 75.85 %, 18. 45 %, 77.68 %, 24.41%, 3.64% and at the dose of 100 ng/mL, the inhibitory rates were 49.65 %, 16.86 %, 66.97 %, 13.39 %, 7.16 % and 59.78 %, 1.28 %, 61.86 %, 2.08 %, 1.44 %, respectively. It is concluded that the component F022 of Radix Isatidis has the strongest anti-endotoxin effect.