Abstract: In this work, a new idea for separating or purifying hydrogen from gas mixture was proposed. As the hydrate formation pressures for different gas components at the same temperature are different from each other, the gas mixture can be separated partially by forming hydrate. This technology is especially suitable for purifying hydrogen, as hydrogen can not form hydrate while other components can. Schematics for purifying hydrogen by forming hydrate were given. A series of fundamental experiments were performed,which showed that it is a promising technology to separate or purify hydrogen by forming hydrate.