Hydrothermal bio-char (ht-biochar) produced from hydrothermal carbonization at different temperatures (200℃, 240℃, 280℃, 320℃ and 360℃) were used as material. Chemical composition, kinetic parameters, combustion index were applied in evaluating the combustion characteristics of ht-biochar.The effects of hydrothermal temperature on the combustion characteristics were also studied. It can be concluded that with the temperature increasing from 200℃ to 360℃, the weight ratio of fixed carbon to volatiles in ht-biochar was increased from 0.34 to 1.2, accompanying with the decrease of O/C (mol/mol) and H/C (mol/mol) from 0.5 and 1.17 to 0.07 and 0.67, respectively. The increase of temperature deepened the coalification degree of ht-biochar. When the hydrothermal temperature was amounted to 320℃, the chemical composition of ht-biochar resembled that of bitumite. At elevated temperature, combustion index Z of ht-biochar was decreased from 3.49×10-2 to 6.64×10-3， indicating that the increase of temperature reduced the combustion activity, which could be confirmed by the variation of chemical composition and calculation results of kinetic parameters. This proved that dimensionless combustion index Z could be used to rate the combustion characteristics accurately.