As a renewable energy source, natural hydrogen is considered an ideal alternative to traditional fossil fuels, making it highly significant for the global energy transition and for responding to climate change. However, the understanding of the “hydrogen system” is still in its infancy in terms of sources, migration, and accumulation. This paper examines the genesis of natural hydrogen by analyzing five mechanisms: water- rock reactions, deep- earth degassing, water radiolysis, thermal cracking of sedimentary organic matter, and microbial activity. Among these, water- rock reactions involving iron- bearing minerals and deep- earth degassing are probably the most common pathways for large- scale natural hydrogen production in the crust. This study summarizes the distribution characteristics and potential sources of natural hydrogen in subsurface and surface environments and offers a preliminary discussion of the migration and dissipation processes of natural hydrogen in geological bodies. The physicochemical properties of hydrogen in geological solids and fluids are the key to revealing the mechanisms of hydrogen accumulation. The paper reviews current exploration technologies, including geophysical, remote sensing, and geochemical methods, with a special emphasis on using geochemical exploration techniques to survey for shallow- surface hydrogen. We propose that the investigation of surface hydrogen leakage, through effective detection and monitoring technologies, a perfect index system, and reasonable evaluation methods, is a key work direction for natural hydrogen exploration at this stage.