Abstract: HHF-217 TYPE NUCLEAR RADIATIoN THICKNEss GAUGE Ou Xugui（shanghai Institute of Process Automation Instrumentation,200233）ABSTTRACT A nuclear radiation thickness gauge is intreduced．The measuring system is based on the absorp-tion of low-energy Υ- ray.The gauge is applied for measurement thickness of iron or steel on line. Themethod and reason of automatic change amplifier are described．The calibration method and result ofcharacteristic measurement are described.Key words low-energy Υ- ray nuclear radiation thickness gauge