Abstract:Genome editing technologies are invaluable tools for understanding the function of genes in development and disease. In recent years， the programmable site-specific DNA endonucleases， including zinc finger nucleases (ZFNs)， transcription activator-like effector nucleases (TALENs) and the clustered， regularly interspaced short palindromic-repeat (CRISPR) system， have gained tremendous popularity and become widely used. In particular due to its simplicity and robustness， the CRISPR-Cas9 systems has swiftly become the most commonly used tool for efficient genome editing of bacteria， plants， cell lines， primary cells and animal species ranging from Drosophila to primates. Supported by “Strategic Priority Research Program” of the Chinese Academy of Sciences (CAS)，research teams at CAS have made a series of breakthroughs in the application and improvement of CRISPR-Cas9 system. Here we review these progresses.