The massive consumption of fossil fuels has caused the excessive emission of greenhouse gases and caused serious environmental issues. It is urgent to optimize the energy structure, develop clean energy and achieve "low-carbon" development. Hydrogen energy is one of the most ideal fuels to replace traditional fossil fuels. The application of hydrogen energy in fuel and non-fuel fields is reviewed in detail based on the basic principles of hydrogen energy. Among them, applications as fuels include fuel cells, thermal power plants, and aircraft, while applications as non-fuels include chemical synthesis, petroleum refining, and the metallurgical industry. In combustion applications, the structure of fuel cells needs to be further optimized. The design of a hydrogen- doped natural gas burner and the research on large-scale hydrogen-doped combustion should be carried out. At the same time, it is necessary to develop the hybrid combustion technology of hydrogen and other aviation fuels to improve the applicability of hydrogen energy to aviation. In non-combustion applications, when hydrogen is used as a chemical feedstock, the cost of the hydrogen source should be considered. When a hydrogen reduction catalyst is used as the reducing agent in the petroleum refining and metallurgy industry, its service life should be considered. The technical challenges of hydrogen safety and hydrogen energy application are discussed. The safety of hydrogen should be emphasized in both combustion and non-combustion applications. The future development direction of hydrogen energy application has been prospected.