Combustion characteristics and kinetics of bio-tar before and after catalytic upgrading were studied on a thermogravimetric apparatus. The results showed that the combustion process was divided into four stages: light organics volatilization, volatilization content combustion, less volatilization content combustion and residue combustion. Weight loss in the first two stages of raw tar was about 75%, whereas that of tar after upgrading was about 90%. With the increasing heating rates, weight loss rate increased heavily along with significantly enhanced combustion stability. According to thermogravimetric curve calculation kinetic parameters, activation energy of upgrading tar was lowered and in agreement with that from TG analysis. The gas from combustion was analyzed by Fourier transform infrared spectroscopy method, which showed the gaseous products generated in three phases of 241~380℃, 380~500℃ and 500~600℃.