The invention discloses laundry liquid and a preparation method thereof. Mild surfactants with mild washing property, high decontamination capacity, no pollution on the environment, such as fatty alcohol-polyoxyethylene ether (AEO9), dodecyl dimethylaminoacetate (BS-12), dodecyl dimethyl benzyl ammonium chloride (1227), distearyl dimethyl ammonium chloride (D1821), polyethylene glycol 6000DS diester, coconut oil diethanolamine (6501) and the like are prepared into the laundry liquid according to a certain proportion and a process; clothes washed by the laundry liquid have soft textile fibers and comfortable wear; and the laundry liquid is mainly used for washing personal clothes, sheets and bedding bags of households, sheets and bedding bags of hotels and the like.