The invention discloses a modification method for heavy components of methanol-based gasoline, aiming to overcome the problems that the content of heavy components, especially durene in the methanol-based gasoline is higher. The method comprises the following steps: performing transalkylation reaction to methanol-based gasoline heavy components with benzene at the presence of a catalyst, wherein the mole ratio of benzene to the methanol-based gasoline heavy components is (3-6) to 1, the transalkylation reaction is carried out under the conditions that the temperature is at 380DEG C-450DEG C, the idle speed is 1.0h<-1>-4.0<-1>, and the pressure is at 0.5Mpa-5.0Mpa, and the catalyst for transalkylation reaction is a molecular sieve catalyst modified by rare earth and citric acid. Through using the method, polymethyl benzene, especially durene in the heavy components can be converted into aromatic hydrocarbon taking C8 and C9 as mains, and the yield of the methanol-based gasoline can be greatly improved.