The invention discloses a transcription activator-like effector nuclease mediating targeted knockout of a colitis related gene Ace2, a coding sequence and an application of the nuclease. The transcription activator-like effector nuclease disclosed by the invention comprises a pair of transcription activator-like effector proteins and a monomer or a catalytic subunit of a DNA incision enzyme, wherein the monomer or the catalytic subunit are separately fused with the proteins. The transcription activator-like effector proteins have the functions of separately identifying and cutting two adjacent loca of an Ace2 gene of a mouse to efficiently and specifically realize targeted knockout of the Ace2 gene so as to quickly obtain a colitis model of the mouse, thereby providing a good genetic resource for research on colitis.