The invention discloses a method for improving aureomycin yield as well as a recombinant expression vector and a genetic engineering bacterium of the aureomycin. The recombinant expression vector is constructed by utilizing an FADH2(Flavin Adenine Dinucleotide) dependent chloride enzyme gene ctcP and an FAD reductase gene ctcQ; the recombinant expression vector is transferred to streptomycesaureofaciens to obtain the genetic engineering bacterium of the high-yield aureomycin; and the bottleneck of chlorination in an aureomycin synthetic route is broken by over-expression of the FADH2 dependent chloride enzyme gene ctcP and the FAD reductase gene ctcQ of the obtained engineering strain, so that the yield of the aureomycin in streptomyces aureus is improved. The strain is obtained for laying a foundation for improving the aureomycin yield and reducing the production cost of the aureomycin.