The invention provides an insulation plate ultrasonic detection device. The insulation plate ultrasonic detection device comprises an ultrasonic probe, a probe wedge block, a coupling agent spraying device, a coupling agent recovery device and a circulation system; the ultrasonic probe is embedded in the position, close to the middle, of the probe wedge block; the coupling agent spraying device and the coupling agent recovery device are located at the two ends of the probe wedge block respectively; a first port of the circulation system communicates with the inlet end of the coupling agent spraying device, thereby carrying out pressurization operation on the spraying device, so that a coupling agent in the spraying device flows to a coupling interface of the measuring end of the ultrasonicprobe and a to-be-tested piece under the action of a pressure; and a second port of the circulation system communicates with the outlet end of the coupling agent recovery device, so that a negative pressure is generated in the coupling agent recovery device, and then the coupling agent flowing out of the coupling interface flows back into the coupling agent recovery device. According to the device, the usage amount of the coupling agent is reduced while automatic spraying of the coupling agent is realized, and the cleaning workload after ultrasonic detection is also reduced.