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Klebsiella pneumoniae (Kp) is widely distributed in nature. Pathogenic Kp can cause a wide range of clinical infections, including respiratory infection, bloodstream infection, liver abscess, urinary system infection and so on. As a famous "plasmid collector", Kp can habor different types of plasmids in its genome. As a result, multidrug-resistant (MDR) strains continue to appear in recent years. Especially, the emergence of hypervirulent MDR (hv-MDR) Kp brings great challenges to clinical treatment. Therefore, the ability of Kp to obtain foreign genes, especially drug resistance and virulence-related genes, has attracted the attention of a large number of scholars. As the major acquired immune system in bacteria, the active clustered regularly interspaced palindromic repeats/CRISPR-associated proteins (CRISPR-Cas) system can effectively block the horizontal transfer of mobile elements into the genome of Kp, especially for transfer ability of conjugative plasmids. In recent years, it has been found that some conjugative plasmids carry anti-CRISPR (Acr) protein to inhibit the activity of the CRISPR-Cas system encoded by host bacteria, escape the host immune recognition, and then can effectively transfer between hosts. The sequenced Kp genome showed that the main types of CRISPR-Cas system in its genome were type I-E and subtype I-E*. Therefore, analysis of the relationship between the CRISPR-Cas distribution and transfer ability of plasmid in Kp and further exploration of the mechanism of Acr protein in regulating the activity of CRISPR-Cas, will provide clues and direction to the dynamics of its genome evolution. It will eventually provide clinical guidance for the prevention and control of hv-MDR Kp. [ABSTRACT FROM AUTHOR]