Now a new organic composite scale inhibitor has been developed, which has high scale inhibition and dispersion performance compared with the early SHMP, etc., and can safely operate inorganic carbonate scale within LSI (Langrier index) 2.6. For sulfate scale, the solubility of organic composite scale inhibitor can be improved. Also because it is a low-phosphorus compound, it will not produce an oxidizing environment on the reverse osmosis concentrated water side after hydrolysis, causing bacterial proliferation, and will not form a secondary pollution of eutrophication to the environment after discharge, and play a role in protecting the environment. At the same time, it has a strong dispersion effect on iron colloid and silica gel, that is, to prevent colloid from fouling the film.