Abstract
The invention provides a system realizing overexpression of target protein. The system contains dihydrofolate reductase deficiency type CHO cells, a folic acid antagonist, a target protein expressionvector and a CRISPRi expression vector, wherein the target protein expression vector comprises a target protein expression box and a DHFR expression box, and the CRISPRi expression vector comprises agRNA box and a dCas9 expression box. With the system realizing overexpression of target protein, the yield of target protein can be obviously improved, and the time for gene amplification is shortened.