To study the effect of chinese herbal medicine preventing gallstone formation, morphology of livers and gallbladders as well as conjugated bile acids of the bile. 58 female guinea pigs were randomly divided into three groups. The control group was fed on normal diet; the lithogenous groups was high cholesterol diet (HCD) and the antilithic group was high cholesterol and the chinese herbal medicine capsule (13.5 g/kg). 8 weeks later the guinea pigs were killed. Liver and gallbladder were removed for light and electroscope observation. Gallbladder bile were withdrawn and gallbladder were collected. The minute construction of gallstones were observed by scanning electron microscope and gallstone components were quantified by Fourier Transform Infrand Spectros Copy (FT-IR). The morphology of liver and gallbladder were observed by light microscope and transmission electron microscope. Conjugated bile acid of biles were determined by Thin-layer Chromatograph. The effect of chinese herbal medicine preventing gallstone formation, morphololgy of livers and gallbladders as well as conjugated bile acids of the bile were also observed. We measured conjugated bile acids in all groups and found that decreased in lithogenic group and increased notably in antilithic group (P＜0.01). The gallstone formation rate was 100% when the animals were fed on HCD in lithogenic group. The rate decreased to 5.3% when the animals were fed on HCD and Chinese herbal medicine capsule inantilithic group. It indicates that changes in diet is an important factor in the process of gallstone formation and the chinese herbal medicine can prevent gallstone formation effectively.