The invention discloses a hydrogen energy system, belonging to the chemical field, which is characterized in that substance capable of reacting with water to generate hydrogen under certain condition is stored in a reactor; when hydrogen is required to generate, water is added into the reactor. Hydrogen generated after reaction is escaped from the reactor, and other products are left in the reactor and sent to a reduction system for reduction; and reduced reactant is stored in the reactor for standby at any time so as to realize the purpose of continuously storing and transferring energy and recycling the substance. The technical has the advantages that the substance capable of directly reacting with water to generate hydrogen is stored instead of storing hydrogen; because alkali metal elements, magnesium, aluminium and the like are solid, compared with the hydrogen having same quality under normal temperature and pressure, volume is smaller, which is equivalent to the situation that small volume stores a great quantity of hydrogen, and is safer and easier than that hydrogen is directly stored. Thus, the hydrogen-saving system is flexible to use.