Abstract: Ninety six crossbred Duroc×(Landrace×Largewhite) weanling piglets weighing (5.27±0.49) kg were randomly allocated to 4 treatments , 4 replicates of 6 piglets each (half male, half female). Piglets per treatments were respectively fed one of the experimental diets supplemented with glutamine dipeptide at a level of 0%, 0.125%, 0.25% and 0.50% , to study effect of the different levels of glutamine dipeptide in diet on the growth performance, cell immunity and serum biochemical index of weanling piglets. The result indicated that the supplement of 0.125%~0.50% glutamine dipeptide in diets improved feed conversion rate, strengthened cell immunity, increased serum growth hormone concentration and decreased cortisol concentration. High supplemental level of glutamine dipeptide (0.50%) significantly increased serum SOD value. Optimum supplemental level of glutamine dipeptide in diet for weanling piglets were 0125% ~0.25%.