Hydrazine hydrate reduction of metal is mainly applied in the preparation of metal nanoparticles, recovery of metal ions in spent liquid and nuclear fuel. This article reviews the research progress in recent years on the preparation of nano metal materials,the recovery and reuse of metal ions and the used nuclear fuel by hydrazine hydrate as reducing agent or complexing agent in liquid phase reduction process. In liquid phase reduction,the differences and the related mechanisms,characteristics and influencing factors between acidic and alkaline conditions are analyzed and summarized in the pro...