Abstract: Normally there is a lot of electromagnetic interference on our industrial site where ultrasonic test machine is mounted. So it is an extremely important task for researchers whether in design or commissioning phase to suppress or eliminate it from useful ultrasonic echo signals. Here based on the analysis and classification to common electromagnetic interference, this article provides us some valid protective measures especially against largescale ultrasonic test machine with authors many years of related work experience. Meanwhile the effectiveness of these measures has been fully validated in the laboratory tests and customer site tests, which also brings important guiding significance for UT detection system design and practice in antiinterference performance.