Objective To study the biotransformation regulation and pharmacological effect of swertiamarin and its metabolite in incubated system of human intestinal flora. Methods Incubated system of human intestinal flora was utilized to research the intestinal metabolism of swertiamarin. Furthermore, mutagenic test and anti-mutagenic test were carried out to research the activity relationship of swertiamarin and its metabolite. Results Gentianine was found in the metabolites of swertiamarin. The pharmacological experiment indicated that swertiamarin and its metabolite both had good anti- mutagenic effect. Conclusion Swertiamarin is partly metabolized to gentianine after oral administration. They show similar anti-mutagenicity effects. Objective To study the biotransformation regulation and pharmacological effect of swertiamarin and its metabolite in incubated system of human intestinal flora. Methods Incubated system of human intestinal flora was utilized to research the intestinal metabolism of swertiamarin. Furthermore, mutagenic test and anti-mutagenic test were carried Out to research the activity relationship of swertiamarin and its metabolite. Results Gentianine was found in the metabolites of swertiamarin. The pharmacological experiment that that swertiamarin and its metabolite both had good anti mutagenic effect. Conclusion Swertiamarin is partly metabolized to gentianine after oral administration. They show similar anti-mutagenicity effects.