Nanocrystalline ZSM-5 with mesoporosity was synthesized within a short reaction time using triethoxyphenylsilane as the mesopore structure directing agent via a direct one-step hydrothermal method. With the addition of the organosilane, the growth of the zeolite grain was restrained, which led to the formation of intercrystal mesoporosity. These zeolite nanocrystals are designed to enhance the adsorption properties by increasing porosity. Their adsorption performance was measured via the static adsorption method with toluene as a model gas on an intelligent gravimetric analyzer.