The invention discloses a gene for coding a glutamine dipeptide biosynthetic enzyme and application thereof. The nucleotide sequence of the gene is shown as SEQ ID NO.1. The invention further discloses an amino acid sequence coded by the gene, and provides a recombinant vector containing the gene, recombinant escherichia coli, and a method for performing biotransformation to synthesize the glutamine dipeptide by using the gene. The gene and the application of a recombinant bacterial strain of the gene have the advantages of high mol conversion rate, high reaction speed, easy separation, low cost and the like. In the synthesis method, the maximum mol conversion rate of the glutamine dipeptide can reach 83.3 percent; meanwhile, the thalli can be applied to the catalytic synthesis of the glutamine dipeptide again after the circulation recovery; in addition, the catalytic activity is stable. Therefore high market competitive power and application values are realized; a foundation is laid for the industrial production of the glutamine dipeptide.