The invention discloses a method for preparing aromatic methyl ether, which comprises the step of reacting an aromatic phenol compound, caustic alkali, water and mono-chloro methane for 2hours to 8hours at the temperature of 60 DEG C to 100 DEG C under the pressure of 0.5Mpa to 2.5Mpa, so as to obtain the aromatic methyl ether, wherein the molar ratio of the aromatic phenol compound to the caustic alkali to the mono-chloro methane is 1:(1.0-2.0):(1.0-5.0), and the weight ratio of the caustic alkali to the water is 1:(4-10). The preparation method disclosed by the invention not only has the advantages that cost is low, yield is high, reaction is easy to implement and the like; by adding the phase transfer catalyst, the gas-liquid two-phase reaction can be effectively prompted, the reaction temperature range is moderate, both the reaction conversion ratio and the selectivity are relatively high, the purity of the aromatic methyl ether can reach more than 99.5%, the reaction yield is 95-97%, and the method has very high value in industrialization. In addition, the problem of exhaust emission in the 1,2-benzo-iso-thiazoline ketone production process is solved, the mono-chloro methane is effectively recycled, and the zero-emission production technology is achieved.