Previous studies have shown that over-production of glutamate pathway is α-KG to glutamate by through the gdh of reduction.Therefore, deleting the gdh gene block the generation of glutamate. The strain with gdh distruped showed no L-gluDH activities, resulting in up to 14.7 times α-KG production than the original strain in flask culture. There results suggest that L-gluDH is the key enzyme in the generation of glutamate. Over-expression of pyruvate carboxylase can enhance CO2 fixed and improve the metabolism stream of pyruvate to oxaloacetate. The result is that the strain C. glutamicum KGA-2pXMJ19pep α-KG production increased 15.7% more than the original strain. Our results can be applied in the industrial production of α-KG by using C.glutamate as producer.