Abstract: The zirconium-niobium alloy is hydrided at 880℃.And when zirconium hydride reaches its hydrogen saturation point at that temperature,hydrogen has been continuously supplied to the hydriding fur-nace during the process of slowly cooling.This method can progressively increase the hydrogen content of zircloy hydride and effectively prevent hydride from cracking.The results show that the H/Zr atom ratio of zirconium hydrides is above 1.80 and the samples have no cracking.During the hydriding process,the niobium which is rejected from the zirconium hydride is present as a fine,uniform dispersion.The H/Zr atom ratio is depended on the hydriding temperature and the pressure of hydrogen.It is very important to prevent zirconium hydride from cracking by controlling the rate of cooling and the flow of hydrogen.The X-ray diffraction and metallography analysis results show that the hydride phase is a single ε-phase and the morphol-ogy of ZrHx (x>1.80) appears as a banded,twin structure.