The invention provides an all-organic type engine coolant which comprises glycol, fat carboxylic acid, tricarboxylic acid, benzoic acid, tri (2-ethylhexoic acid) phosphonate, imidazoles compound, defoamer and deionized water. The engine coolant of the invention contains no inorganic salts, such as amines, borate, nitrate, nitrite, silicate, and the like, so the engine coolant is environment-friendly, can prevent all the contacted metal and nonmetal materials in the engine cooling system from being corroded, has an obvious engine coolant effect on various metals, particularly solves the problem that the cast aluminum using a traditional organic acid engine coolant becomes black generally, can be stabled in a relative low density and bigger PH value range, and has the advantages of long-time storage and use.