Abstract: A series of nMoO_x·HZSM-5 single-phase complexes were prepared by incipient wetness impregnation, and characterized by XRD, NH₃-TPD, Py-FTIR, BET and SEM techniques. The n-butane catalytic cracking performance over nMoO_x·HZSM-5 was investigated by using a continuous flowing micro reactor. The results indicate that active component Mo is located in the cross of Z form channel and straight channel of HZSM-5 in the form of MoO_x clusters to generate a nMoO_x·HZSM-5 single-phase complex, causing the contraction of HZSM-5 lattice cell and the reduction in the lattice parameters and cell volume of HZSM-5 as well as the decrease in specific surface area of HZSM-5. The acidity of nMoO_x·HZSM-5 shows an increases firstly and then a decrease with the increasing dosage of active component Mo. The n-butane catalytic cracking conversion over nMoO_x·HZSM-5-0.75% is 73.83% at reaction temperature of 625℃ and gas space velocity of 5600 h^-1, slightly lower than that over HZSM-5. However, the propylene yield over nMoO_x·HZSM-5-0.75% reaches 13.13%, 2 percent points higher than that over HZSM-5, exhibiting a better performance on the promotion of propylene yield.