Tar from biomass pyrolysis is harmful to the gasification system and gas consuming equipment. For the tar conversion, with n-heptane and cyclohexane as model compounds on a fixed-bed reactor, effects of cracking temperature, S/C and residence time on the tar conversion rate were investigated using nickel-based catalyst. The results showed that the conversion rate of n-heptane and cyclohexane increased with temperature increasing between 600-800℃. The conversion rate of n-heptane reached 95% at 750℃, while the conversion rate of cyclohexane reached 88.7%. Vapor amount had some effects on conversion rate, but it could affect the gaseous composition and alleviate the carbon deposition on the catalyst surface. Contact time between model compound and catalyst was extended with residence time increasing. The conversion rate of n-heptane and cyclohexane increased when the residence time increased. The results show nickel-based catalyst(Z417) has better catalytic effects on model compounds of biomass tar such as n-heptane and cyclohexane.