The invention relates to a rapid construction method of a conditional gene knockout animal model, which is implemented by using a CRISPR / Cas9 technology. The specific method can be implemented as follows: designing a gRNA target spot sequence, for a to-be-knocked-out gene of an animal, of a CRISPR / Cas9 system, designing a corresponding promoter, constructing a plasmid, thereby implementing conditional gene knockout. According to the invention, the rapid, efficient, simple, feasible, economic, efficient, and wide-applicable-scope construction of a conditional gene knockout animal model can be realized, and the defects existing in traditional methods (specific recombination enzyme system Cre-LoxP) can be overcome.