The utility model discloses an endoscope casing which comprises a casing used for an endoscope probe to penetrate in, a lens installed at the front end of the casing, and a flange disk fixed at the rear end of the casing. A gas guide channel, a water guide channel and a treatment channel are arranged inside the casing along the length direction; a flow guide block is arranged at the outer side of the end wall of the lens; two flow guide grooves respectively communicated with the gas guide channel and the water guide channel are arranged on the inner side wall of the flow guide block; and the treatment channel runs through the flow guide block. Compared with prior art, the endoscope casing has the advantages that the endoscope casing has good cleaning effect; the area cleaned is big; during cleaning, the endoscope casing is convenient to use and the casing is unnecessary to be rotated, so the pain of the patient during the treatment process can be lightened.