A water jet arthroscope, comprising a pump body assembly (1), a water jet assembly (2), an endoscope module (3), and a cryoablation assembly (4). The water jet assembly (2) is connected to the pump body assembly (1); the endoscope module (3) is connected to the water jet assembly (2); the cryoablation assembly (4) comprises a cryo-switch ball valve (41), a cryoablation catheter (42), and a cryo-balloon (43); the cryo-switch ball valve (41) is provided on the water jet assembly (2); one end of the cryoablation catheter (42) is connected to an outlet of the cryo-switch ball valve (41), and the other end thereof passes through the endoscope module (3; the cryo-balloon (43) is provided at the other end of the cryoablation catheter (42). The water jet arthroscope is easy to operate by a doctor, causes less bleeding, achieves quick postoperative recovery of a patient, shortens an operation duration, is high in treatment effectiveness, reduces severe complications such as thrombosis, and lowers the pain level of the patient; moreover, the doctor and an observer can view an image of the knee of the patient in real time by means of an external workstation and can examine the knee of the patient in detail, so that the operation safety is increased.