ZSM-5 zeolites with modified acidity and diffusivity are employed as catalysts for the shape-selective alkylation of toluene with ethanol to para-ethyltoluene (p-ET). To avoid pore blocking and loss of active sites caused by traditional methods of enhancing para-selectivity using modifiers, here, we constructed twin intergrowth structured ZSM-5 (Z5-T), achieving modulation of the inherent acidity and diffusivity through interface engineering. The characterization results demonstrate that due to the intergrowth interface, the Z5-T catalyst forms more inherent Lewis acid sites and also renders more sinusoidal channels opened to the surface. Z5-T with an appropriate acidity and enhanced shape-selectivity inhibits side reactions such as isomerization and coke formation, demonstrating improved p-ET selectivity (>90%) and catalytic stability (>200 h) in the alkylation of toluene with ethanol.