Salt stress induced Gamma-aminobutyric acid (GABA) accumulation in maize plants. The germination of maize seeds was inhibited seriously by NaCl treatment, while exogenous GABA reduced the inhibition of NaCl on the seeds germination. Effects on SOD, POD and CAT activity of GABA were detected. 1-2 mmol/L GABA induced the increase of the activity of SOD, POD and CAT about 20%. Because of SOD, CAT and POD are important protective enzymes which can eliminate active oxygen, so GABA can alleviate the damage of salt stress through promoting the activity of the protective enzyme system.