A series of hierarchical mesoporous ZSM-5 zeolites with different morphology were successfully syn-thesized by the CO2-in-water microemulsion method, and mesoporosity was formed without organotemplate. The dif-ferent synthesis conditions, including silica alumina molar ratio, stirring time and compressed CO2 pressure, were sys-tematically investigated to discuss the influence of these conditions on the morphology of ZSM-5 zeolite. The resultingsamples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupledplasma (ICP) and nitrogen adsorption-desorption measurement. XRD results indicated that compressed CO2 route forthe synthesis of MFI zeolites had a fast crystallization rate and good crystallinity. SEM images showed that the ZSM-5hierarchical mesoporous ZSM-5 zeolite had a uniform chain-like crystal morphology, whereas silicalite-1 displayed amonodisperse crystal morphology. In addition, the nitrogen adsorption-desorption measurement provided sufficientevidence for the presence of hierarchical mesopores in ZSM-5 zeolite.