By comparing the difference of bile flow and bile acid components between high-fat and normal rats, we tried to reveal the basis of hypothesis which biliary tract adverseness is the central link of obesity. Methods：Building nutritional obesity rat model by high fat diet. Bile duct intubation operation was implemented to collect bile and then compare the bile flow difference. UPLC-MS was used to compare the content of different kinds of bile acid components. Results： Both total and individual test point bile flow of obese rats were lower than those of normal rats. The content of bile acids that had cholagogic effect and promoting fat metabolism in high-fat diet rats reduced significantly. Conclusion： Intaking excessive high-fat diet can increase the burden of bile, resulting in biliary tract adverseness, an unsmooth flow and changes of bile acid components. Long-term imbalance of lipid metabolism will finally leads to obesity.