Fresh ZSM-5 zeolite catalysts were pretreated at 460℃ and 500℃ with various cumulative amount of water feed (CAWF) in a ifxed bed reactor. The catalytic process was carried out under the following conditions: a temperature of 480℃; a methanol WHSV of 3 h-1; a methanol partial pressure of 30 kPa; and a time on stream of 12 h, 24 h and 48 h, respectively. The BET parameters of catalysts and diffusion coefficients of toluene showed that there were two types of mesopores generated under different hydrothermal conditions. Mild temperature and moderate CAWF conditions led to extal open mesopores which could be entered from the extal surface of the zeolite, while a high temperature or a high CAWF condition resulted in the generation of macropores or intal isolated mesopores, which were occluded in the microporous matrix. The TGA results showed that catalyst with extal open mesopores had good ability to resist coke accumulation and good performance on propylene selectivity, while the intal isolated mesopores did no contribute to the increased diffusivity of reactants and products.