CRISPR/ Cas9 technology has driven the development of various fields in life science. With continuous deepening of its understanding, researchers have made multiple improvements and optimizations to adapt to various application scenarios. The optimization of CRISPR/ Cas9 technology has also provided breakthroughs in the establishment of genetically modified mouse models. This article briefly reviews the development process of CRISPR/ Cas9 technology and summarizes optimization strategies of CRISPR/ Cas9, establishment of conditional knockout / knockin gene-modified mouse models, and delivery systems for CRISPR/ Cas9 elements and HDR templates.