Abstract: In connection with the ultrasonic examination characteristics for cast iron dryers，the scan plan to solve the ultrasonic examination of cast iron dryers was provided. The ZGZ series test-piece for double crystal sensor, the test-piece of the long horizontal bores, the contrast test-piece of the long horizontal bores and the contrast slot test-piece of the dryer were manufactured. The small angle double crystal longitudinal wave sensor could examine the volume defects of  3 mm equivalent diameters, and the big angle double crystal longitudinal wave sensor could examine deep 2 mm face crack of the body and the transition area. through that the sensitivity of various sensors was analyzed. The engineering examples proved the possibility and effectiveness for the cast iron dryer testing by ultrasonic testing technique.