Abstract: This trial conducted to study the effects of alanyl-glutamine (Ala-Gln) on growth performance and serum biochemical indexes of weaned piglets. Forty eight crossbred Landrace×Largewhite weaned piglets at the age of 21 day were selected and randomly divided into 4 treatments with 6 replicates 2 piglets (a male, a female). Group A (control) was fed the basal diet and Group B, C and D as three trial groups were fed the basal diet added 0.1%, 0.3% and 0.5% Ala-Gln respectively and the trial lasted 20 days. The results showed that average daily gain and feed conversion rate were significantly increased（P<0.05） by adding 0.1% Ala-Gln and level of serum glucose, triglyceride, total cholesterol and blood urea nitrogen were decreased and serum total protein was increased within the framework of physiological by adding 0.1%,0.3% and 0.5% Ala-Gln. With the increasing Ala-Gln supplementation levels, average daily gain and feed conversion rate were increased (quadratic, P=0.042 and 0.043) at 21~31 day and level of serum glucose at 31 and 41 day and level of serum triglyceride and total cholesterol and blood urea nitrogen at 31 day were decreased (linear, P=0.034,0.001,0.008, 0.001 and 0.062) and supplementation 0.3% Ala-Gln had the best effect. The results indicated the mechanism of Ala-Gln promoting growth performance in weaned piglets.