Abstract: OBJECTIVE To investigate into the pharmacological effect and chemical composition of the organic acid of Radix Ranunculns Ternati.METHOD In vitro susceptibility test on tuberculosis bacteria and GC-MS technique were used. RESULT The organic acid of the drug had anti-tuberculosis effect with dose-effect relationship. GC-MS analysis indicated that multiple kinds of organic acid existed. CONCLUSION The organic acid of the drug is responsible for its anti-tuberculosis effect.