The invention provides a neutral water-based cleaning agent and a preparation method thereof. The neutral water-based cleaning agent comprises the following components in percentage by mass: 0.5-1.5%, preferably 1%, of aliphatic alcohol alkoxy surfactant, 1-5%, preferably 3%, of aliphatic alcohol polyoxyethylene ether surfactant, 1-5%, preferably 3%, of ployether surfactant, and 0.5-1%, preferably 0.7%, of linear alkyl benzene sodium sulfonate. In the invention, as nonionic surfactants are compounded with anionic surfactants, surface tension of the cleaning agent is reduced, and pH of the cleaning agent is kept neutral; the neutral water-based cleaning agent disclosed by the invention has a good cleaning effect on polar and nonpolar pollutants, and can achieve an unexpected beneficial effect in cleaning slits by adopting physical cleaning means such as ultrasonic cleaning, high-pressure spraying, brushing and the like.