The invention relates to a vector, an engineering strain and a method for producing L(+)-2-aminobutyric acid. The vector is a recombinant vector containing a threonine dehydratase coding gene, an L-amino acid dehydrogenase gene and appropriate vector segments. The engineering strain is obtained by transforming host bacteria by the recombinant vector. The L(+)-2-aminobutyric acid is prepared by fermentation culture of the engineering strain. The engineering strain is fermentation-cultured by glucose as a raw material to produce L(+)-2-aminobutyric acid. The method has the advantages of low cost, high product concentration, no by-product, easy product purification, and good industrial application feasibility.