The invention relates to a process for preparing a benzoic ether plasticizer by using a slurry method. In the process, benzoic acid and alcohol react in the presence of a catalyst to produce a benzoic ether plasticizer. The process is characterized by comprising the following steps of: slurrying solid granular, powdery or blocky raw material benzoic acid in alcohol; after the slurrying is finished, adjusting the mole ratio of the alcohol to the benzoic acid to be (1-4):1; then mixing with a conventional catalyst which accounts for 0.1-0.2% of the mass of the raw material benzoic acid, raisingthe temperature to 210-240 DEG C gradually while stirring in a reactor with an oil-water separator, reacting for 1-4h under heat insulation and ending the reaction till the acid value is lower than 1; and then performing conventional dealcoholization and purification treatment to obtain the benzoic ether plasticizer. The invention has the advantages that the original solid benzoic acid raw material is slurried under the condition that original equipment is not necessary to change completely, therefore, the reaction contact area of two phases is increased, the reaction speed is increased greatly, the efficiency is increased and the energy is saved.