Alloy 617 is the leading candidate material to prolong the design life for Intermediate Heat Exchanger (IHX) of helium-cooled a Very High Temperature Reactor (VHTR) nuclear systems. The purpose of this work is to investigate the influences of temperature and hold time on the creep-fatigue behavior of Alloy 617. The creep-fatigue tests were performed at 900℃. And the strain range imposed in this investigation was from 0.6% to 1.5%(Rε of -1), with tension hold varies from 0-5mins. A constant strain rate of 10-3/s was used. For the Creep-fatigue tests, creep-fatigue behavior performed on base metal specimens of Alloy 617 were evaluated.