The invention relates to an ultraviolet ray and cavitation oxidation synergistic water disinfection device. The device comprises a stator, a rotor, a rotating shaft, ultraviolet ray emitters, an oxidant conveying device and ultrasonic transducers, the stator is a sealed cylinder, the ultrasonic transducers are arranged on the inner wall of the stator, the ultraviolet ray emitters are arranged on the end surfaces of the two sides of the stator, a water outlet and a water inlet are formed in the end faces of the two sides of the stator respectively, one side of the water inlet is connected with an oxidizing agent conveying device, the rotating shaft is installed in the stator, the rotor is located in the stator and installed on the rotating shaft, blades are distributed on the rotor, cavities are formed in the blades, and cavitation through holes are distributed in the blades and located in the two opposite sides of the cavities. According to the device, water is treated by efficiently couplingfour processes of hydrodynamic cavitation, ultrasonic cavitation, ultraviolet rays and oxidation, the effect is good, the magnifiability is high, the treatment capacity is large, the cost is low, no secondary pollution is generated, continuous operation can be achieved, and therefore the device has wide application prospects in the field of water disinfection.