Hierarchical ZSM-5 zeolites have been receiving increasing attention from both fundamental research and industrial applications. From the chemical engineering viewpoint, the introduction of building block of ZSM-5 could give consideration to both external surface acidities and diffusion properties which are important in parallel sequence reaction for the final product distribution. In this work, hierarchical ZSM-5 with different sizes of building blocks were successfully prepared by tuning the water/silica ratio during the synthesis. With varying the size of building blocks, the diffusion property and external surface acidity were finely regulated, and it significantly influences the performances of ZSM-5 during catalytic cracking reaction. The catalyst with proper size of building blocks exhibited the optimized yield of olefins and lowest carbon deposition during 72 h reaction in catalytic cracking of i-butane. The strategy proposed herein could be helpful for the engineering design of hierarchical zeolites for industrially important catalytic reactions.