Abstract: Most analog ultrasonic flaw detectors importing from foreign country are gain model. ECHOPE-220 and 230 ultrasonic instruments producing by ShanTou city ultrasonic instructions institute is gain model. Most customers in our country used the instruments. They are not customary to set down and use curve by using the instruments indirectly. When we modified relative reading panel of attenuator of these instructions, we can use the instruments as attenuation model.