Method for knocking out two mir-505 alleles

The invention relates to a method for knocking out two mir-505 alleles. The method comprises the following steps: constructing two targeting vectors for mir-505 alleles, replacing and knocking one mir-505 allele out of a cell of a mammal by mediating one targeting vector by using a CRISPR/Cas system, obtaining the cell with one mir-505 allele being knocked out by adopting a G418 resistance screening method, knocking another mir-505 allele out of the cell of the mammal by mediating another green fluorescent targeting vector by using the CRISPR/Cas system based on the cells, and obtaining the cell with two mir-505 alleles being knocked out by adopting a fluorescence screening method. The method is helpful to constructing a gene knocked-out cell model and has good application prospect.