In recent years, with the development of gene editing technology, the site-specific genome can be modified. The curability of genetic disease may be achieved by the use of gene editing techniques. As the simplicity, high specificity and economical efficiency, much attention has been paid to the CRISPR/Cas9 system, which was been widely used in research of molecular biology and other fields of life science. In this review, the mechanism for CR1SPR/Cas9 system and the progress of gene therapy, such as for hemophilia, betathalassaemia and chronic myeloid leukemia were summarized briefly.