Abstract: Taking grass carp (Ctenopharyngodon idellus)fingerling with hepatobiliary syndrome as sample and Chinese herbal formula as test drug, we designed 3 poison bait groups mixed with 0.50%, 0.75% and 1.00% concentration of Chinese herbal formula, one common feed group without Chinese herbal formula and one green feed group to feed the sick fish for 4 weeks, so as to study the control effect of Chinese herbal formula on grass carp hepatobiliary syndrome by histopathology method. The result shows that the liver-lesion tissue of the test fish has many self-soluble necroses and is destroyed dispersively; the liver nuclei moves, accompanying with vacuolar and hydropic degenerations; the survival of the 3 experimental groups and 2 control ones (green feed group and common feed group without Chinese herbal formula) is 60.0%, 80.0%, 96.7%, 36.7% and 16.7%, respectively; the hepatobiliary syndrome of the test fish has obviously ameliorated in experimental groups than in the control; the body color, body surface slime, and the shape, color and texture of liver return to normal; the dorsal fin, caudal fin and edges turn white; the blood extravasation and congestion in gill disappear; the slime on gill decreases obviously. For the experimental group with 1.00% concentration, the hepatic lobule and hepatocytes of grass carp′s liver have clear boundaries; nuclear membrane and nucleolus of hepatocytes are easily recognized; the nucleolus have moved to the middle of hepatocytes which return to normal gradually.