The invention discloses a method for knocking out MSTN (
myostatin) genes in a targeted manner by utilizing
CRISPR-Cas9. According to the method,
multiple species are subjected to homology comparison, two pairs of MSTN
gene target sequences are selected, two pairs of
DNA double strands which have the sequences different from the target sequences, the same
expression protein and the same BsmBi sticky ends are synthesized according to the design principle of PAM of gRNA, the double strands are connected with pPDNA330 plasmids, a recombinant vector carrying MSTN homologous genes of
multiple species is obtained and is used for detecting the
gene knockout efficiency with a
fluorescent protein expression method, carrier-transfected
receptor cells, having higher knockout efficiency, of
multiple species are selected,
gene knockout and
verification are performed, and simple, efficient and accurate
gene knockout on the MSTN genes of the multiple species is completed.