CRISPR/Cas9 is a set of genome editing tools derived from bacteria, consisting of the Cas9 nuclease and guide RNA (gRNA). Cas9 is responsible for recognizing and cutting DNA, while gRNA ensures precise targeting of specific gene sequences. This system achieves editing of DNA inside the nucleus, allowing scientists to perform gene knockout, insertion, or correction. It is involved in the signal pathways of DNA damage repair and gene expression regulation. By selectively modifying genes, it influences cellular behavior and function. The application of CRISPR/Cas9 is influenced by gene-specific expression, and its accuracy and efficiency are subject to improvements in gRNA design and Cas9 variants.