The invention belongs to the technical field of hydrate application, and provides a hydrate energy storage device and a method based on metal-organic frameworks. The metal-organic frameworks are usedas porous media for generating hydrate, so that holes which are close to the size of unit cells of the hydrate can be supplied, the contact area between components is increased, the temperature and pressure condition required for generating the hydrate are reduced, and the hydrate is generated within short induction time in mild temperature and pressure conditions; the processes of storing gas andreleasing gas are reversible, and the modular structure can be recycled. A multilayer modular structure is used, so that the metal-organic frameworks are fully filled, the space in a reaction vesselis effectively used for storing natural gas and hydrogen gas, and the gas storing and releasing performance of the device is optimized. When the hydrate is decomposed, heat is released by stored ammonia, so that heat required for hydrate decomposition is supplied, and the hydrate decomposition is promoted so as to release gas. Porous medium materials are separated from gas molecules by a filter device, so that the gas purity is guaranteed, and the problem of easiness in blockage of a gas outlet by the porous media is solved.