The invention relates to a 
microwave photocatalytic device for degrading 
wastewater and being capable of keeping high treatment efficient continuously, and belongs to the technical field of 
wastewater treatment. In the conventional 
microwave photocatalytic degrading technology for the industrial 
wastewater containing organic contaminants, the outer lateral surface of a 
quartz tube for shielding a non-polar 
ultraviolet lamp in a device is soaked in wastewater liquid for a long time so as to generate a scale phenomenon, the permeability of the 
quartz tube about the 
ultraviolet light is seriously influenced due to the existence of the scale layer, and the treatment efficient of a 
microwave photocatalytic reaction device is greatly reduced. The microwave photocatalytic device aims at solving the problem. According to the invention, an ultrasonic 
transducer provided with a cage-shaped 
microwave shielding cover is arranged on the inner lateral surface of the sidewall of a microwave photocatalytic reactor, on the premise of not stopping and not disassembling, the scale on the outer lateral surface of the 
quartz tube is instantly ultrasonically cleared through ultrasonic conveyance of a 
liquid medium, therefore the high permeability of the quartz tube about the 
ultraviolet light is kept, and the continuous high efficiency of the microwave photocatalytic degrading reaction device is maintained.