The invention provides a disinfecting detergent and a preparation method thereof. The disinfecting detergent contains didecyldimethylammonium chloride, didecyldimethylammonium bromide, poly(hexamethylene biguanide) hydrochloride, dodecyldimethylbenzylammonium chloride, fatty alcohol-polyoxyethylene ether (9), fatty alcohol polyoxyethylen ether (7), fatty alcohol polyoxyethylen ether (8), alkyl polyglucoside, alkanolamides of fatty acids, lauramidopropyl betaine, essence, citric acid monohydrate food grade and deionized water. The method has the advantages of environmentally-friendliness, combination of disinfection and cleaning, synchronous completion of stain removal and disinfection, safety, unstimulating property, and resource conservation.