The invention discloses the construction of a high-copy and high-expression recombinant plasmid and its application in exogenous gene expression, and relates to the technical field of genetic engineering. In the present invention, the pcDNA3.1(-) plasmid is used as the backbone, and the cumate-cymR inducible expression regulatory unit is loaded between the pUC ori high-copy replicon and the Ampicillin resistance gene, and at the same time, the multiple cloning site downstream of the pET-28a T7 promoter Point, 6xHis coding sequence and T7 transcription termination sequence were inserted downstream of the cumate-cymR regulatory unit to construct a recombinant plasmid DN-001 with high replication and high expression. The recombinant plasmid DN‑001 of the present invention has the advantages of being the most economical, the most convenient, and high yield, making the recombination of gene expression vectors time-saving and labor-saving; it can be applied to the production of large doses of recombinant proteins; at the same time, it effectively suppresses leaky expression, making This vector is especially suitable for the expression of toxic proteins, which makes this vector have broad market prospects.