Abstract: "882" broilers at one-week-old were randomly divided into two groups.Contr ol group (CG) was feeded with distilled water,and experimental group (EG) was feeded with distilled water containing 0.05% GABA.Eath group was heat stress at 32 ℃ every day for 1.5 h.The experiment was conducted for four weeks.The results showed that GABA could affect the performance and physiologic index of the heat stress broiler.Compared with CG,GABA dropped significant respiratory of EG (P<0.01) and improved erythrocyte of broilers of EG (P<0.05).While GA BA could decrease feed conversion ratio of EG (P<0.01) and increase body we ight gain of EG 117.86% as compared with CG (P<0.05).