A method for preparing methylbenzene by alkylating benzene and methanol comprises the following steps: adopting an acidic molecular sieve as a catalyst, adopting gas as carrier gas or adopting a plunger pump as feeding power, maintaining the total airspeed of benzene and methanol to be 0.5 to 5 h<-1> at the reaction temperature of 200 to 600 DEG C and under the pressure of normal pressure to 3 Mpa, and alkylating benzene and methanol to prepare methylbenzene reaction by a catalyst bed layer, wherein the molar ratio of the benzene to the methanol is (0.3-4):1.