Abstract: This test observed growth performance，muscle composition，digestive enzyme and immune system of Carassius auratus Linn. fed diets with aqueous extract of Taraxacum mongolicum Hand-mazz. for 70 days. The results showed that with 4%，2% aqueous extract of Taraxacum mongolicum Hand-mazz. could promote growth; 4%,2% group could improve muscle composition;4%，2% groups could rise significantly activity of diastase and proteinase(P<0.05);4%,2% groups could rise most significantly number(P＜0.01）;4%，2% and 1% groups could not effect content of total protein and triglyceride and activity glutamic-pyruvic transaminase(GPT) in blood serum (P＞0.05);4%，2% groups could rise significantly activity of alkaline phosphatase in blood serum (P<0.05).

Key words: Taraxacum mongolicum Hand-mazz.; Carassius auratus Linn.; growth; muscle composition; digestive enzyme; immunity