The invention relates to a method for achieving HMGCR 
gene knockout based on the 
CRISPR / Cas9 technology. The method is characterized in that two 
CRISPR / Cas9 target sequence aiming at the HMGCR 
gene isdesigned, a gRNA 
single chain is synthesized 
in vitro, annealing is performed to obtain two gRNA double-chain 
DNA target 
insertion fragments, the 
insertion fragments are inserted into PX459 (pSpCas9(BB)-2A-Puro)V2.0 vectors to obtain the two different-locus plasmids of the target HMGCR 
gene; the two plasmids are transfected into PK15 cells, 
puromycin is used to process the cells, the processed 
cell genome DNA is extracted to perform PCR amplification, the PCR product is denatured, annealing is performed, and then T7E1 is used to perform HMGCR 
gene knockout identification. The method has the advantages that method can be used for analyzing the expression conditions of sequence and mRNA after the HMGCR 
gene knockout, whether an off-target phenomenon exists or not can be verified by using amethod combining PCR and T7E1 
enzyme treatment, and accordingly the specificity based on target sequence HMGCR-gRNA can be determined; the method is applicable to 
cell and animal models to achieve fixed-point HMGCR 
gene knockout, has a reference value to the knockout of other genes, and is good in effect, simple, economical, short in time and the like.