Abstract: It relates to the field of molecular biology, and specifically to an isolated nuclease and the use thereof. It further specifically relates to: a nucleic acid and a nucleic acid construct encoding the nuclease, a guide RNA and a nucleic acid construct thereof, and a composition, a recombinant vector, a recombinant host cell and a kit comprising the nuclease. It further specifically relates to: a method for introducing a double-strand break into a targeting gene of a host cell, a method for deleting, replacing or inserting a targeting gene of a host cell, and a method for obtaining a host cell in which a targeting gene is deleted, replaced or inserted.