The catalytic behavior of Bi-impregnated HZSM-5 zeolites in propylene aroma-tization and the surface properties of the zeoh’tes were determined by microreactor, XRD, XPS, NH3-TPD and IR-TPD. The mechanism of the reaction and the effect of surface properties of the zeolites on the reaction were also investigated. Experimental data showed that Bi-impregnation made the strength of B-acid sites decrease, the strength of L-acid sites and the concentration of both strong B-acid sites and strong L-acid sites increase. Bi-impregnation also induced sub-strong acid sites. These were the factors that made the aromatic products of the reaction increase. The strong interaction between the impregnant and zeolite surface reached maximum at Bi2O3 = 3.5 wt%. Above this value, covering effect of impregnant caused a decrease of aromatic products. The catalytic behavior of Bi-impregnated HZSM-5 zeolites in propylene aroma-tization and the surface properties of the zeoh’tes were determined by microreactor, XRD, XPS, NH3-TPD and IR-TPD. The mechanism of the reaction and the effect of surface properties of the zeolites on the reaction were also investigated. The experimental data showed that Bi-impregnation made the strength of B-acid sites decrease, the strength of L-acid sites and the concentration of both strong B-acid sites and strong L These were the factors that made the aromatic products of the reaction increase. The strong interaction between the impregnant and zeolite surface reached maximum at Bi2O3 = 3.5 wt%. Above this value, covering effect of impregnant caused a decrease of aromatic products.