Abstract: Catalytic cracking experiments were performed for bio-oil model compounds (acetic acid, guaiacol, n-heptane and hexamethylene, etc) using HZSM-5 molecular sieve catalyst at 550℃, aiming to study the reaction mechanism and catalyst properties. The results show that the main product for catalytic cracking of n-heptane and hexamethylene is aromatics (53% and 91%, respectively in area). Catalytic cracking reaction occurs more easily for those oxygen-free model compounds. The aromatics content increase effectively (from 12% to 90% in area) with increasing addition of catalyst for acetic acid. The guaiacol structure is quite complex and the catalyst mainly removes its methoxy group. Increasing the weight of catalyst could lead to aromatics formation more easily.