The present invention relates to a DoxA protein mutant having an amino acid sequence set forth in SEQ ID No. 16, and coding gene thereof. The protein mutant or the coding gene thereof can be used for producing epirubicin. The present invention further relates to a Streptomyces capable of efficiently expressing epirubicin, which is constructed by replacing the dnmV gene of a starting Streptomyces in situ with the avrE gene and mutating the doxA gene of the starting Streptomyces into a gene encoding the protein set forth in SEQ ID No. 16. The fermentation broth of this Streptomyces has an epirubicin potency of up to 102.0 μg/ml.