Abstract: According to Ultrasonic examination of the setting on branch connections, we made two kinds of reference blocks (one is calibration block without welding, the other one is a nozzle simulated block with welding) were made. Compared to the calibration sensitivity on the two kinds of the blocks by different probes, this test offers some reference for the choice of the calibration blocks and making the examination procedure for the ultrasonic test of this kind of welding.