Hydrogen molecule is a promising selective antioxidant gas with significantly preventive effect for many diseases. Current clinical research comprises many diseases including ischemia, arteriosclerosis, diabetes, cancer, Alzheimer's disease etc. This paper focuses on hydrogen effects on the prevention of ischemia-reperfusion injury, inflammation, electrical damage and radiation damage of the nervous system diseases such as metabolic syndrome, and the development of the hydrogen molecular medicine and other aspects of the current situation and prospect are overviewed.