Abstract: As ASG nozzle welding structure is complex, in order to optimize its nondestructive testing, the ultrasonic testing(UT) procedures. The paper desiged whole-size ASG contrastive block(0°and 90°profile) according to RCC-M. The paper also used theoretical analysis and diverse angle probes verification, and got the conclusion that probes with refraction angle of 35°and 45°could cover the whole range of the welding thickness, and find artificial defects on the contrastive block. The result meets RCC-M requirements. In the end, the paper establishes pertinent nondestructive testing procedures according to test result.