Abstract: ZSM-5 as a microporous adsorbent was extensively applied to adsorb toluene. In this paper, ZSM-5 was exchanged with alkali metals Li, Na and K for the purpose of adsorbing toluene. The effects of alkali metals introduced into ZSM-5 on micropore structure and toluene adsorption were studied by characterization technology and mathematical model. In this investigation, the influence of alkali metals on the adsorption of toluene was discussed from four aspects: adsorption capacity, exothermic energy, diffusion resistance and desorption activation energy. Based on the experimental results, it was found that the introduction of alkali metal affected the microporous structure of ZSM-5 with certain rules. The order of pore size, specific surface area and pore volume of ZSM-5 follow Li?ZSM-5 > Na?ZSM-5 > K?ZSM-5 with the increase of ionic radius (Li+<Na+<K+). The static saturated adsorption capacity follow Li?ZSM-5 (0.363mmol/g)>Na?ZSM-5 (0.360mmol/g）>K?ZSM-5 (0.325mmol/g). The constant concentration wave model can well fit the adsorption and diffusion behavior of toluene onto ZSM-5. The steric hindrance and electrostatic binding force play a dominant role in toluene diffusion in ZSM-5 channel at high and low inlet gas concentrations, respectively. At higher inlet concentration (155mg/m3), the influence of alkali metal modification on the internal diffusion resistance onto three adsorbents followed Li?ZSM-5<Na?ZSM-5<K?ZSM-5; while at lower inlet concentration (25mg/m3), the trend was inverse with Li?ZSM-5>Na?ZSM-5>K?ZSM-5. In Combination with desorption kinetics analysis, Na?ZSM-5 shows better regeneration potential due to its large pore size and moderate adsorption strength. In this study, the mechanism of alkali-metals modification on adsorption behavior of toluene was systematically investigated from two aspects of steric hindrance and adsorption strength to provide a certain reference for selecting suitable adsorbent in complex practical environment.