The invention discloses a production method and purpose of 
photocatalysis nanometer active water. The production method comprises preparing photo-catalytic material on a 
solid media and immersing the photo-catalytic material in water, irradiating with 
ultraviolet light to lead the water to produce free radical and outputting the 
photocatalysis nanometer active water. The invention is used for 
plant protection, 
tap water for living, dealing recycle water, treating 
sewage and the like, is also capable of being utilized in 
medical treatment and health care. The free radical in the 
photocatalysis nanometer active water is capable of entering 
human body and 
animal body to directly kill bacterium, 
microorganism and viruses, establishing an 
artificial immune system to prevent and treat various diseases. The photocatalysis nanometer active water does not include any 
chemical composition, is nontoxic, has no harm to 
human body and 
animal body, and can be used for a long term. The invention can prevent and treat diseases by means of 
aerosol, injection, 
oral administration and target-oriented 
drug delivery, can cure various diseases like 
tracheitis, 
hepatitis B, HIV, 
lupus erythematosus, influenza and 
bird flu and the like which are caused by 
bacteria and viruses. Simultaneously, the effects of cleaning focus and preventing 
cancer are perfect. The production method of the photocatalysis nanometer active water is simple, low in cost, and easy to spread and use.