The pyrolysis and combustion of sewage sludge particles (d≤0.25 mm, 0.25 mm＜d ≤0.83 mm and d＞0.83 mm) were analyzed with the thermogravimetric analyzer (TGA, STA 409 model, NETZSCH, Germany) at the heating rate of 20 ℃/min. To determine the chemical characteristics of sewage sludge, elemental and proximate analysis was carried out, and the metal content of the dry sewage sludge was determined. Meanwhile, a new method was developed to calculate pyrolysis kinetic parameters with surface fitting tool in software MATLAB7.11.0 (R2010b). The results have shown that sewage sludge pyrolysis process are divided into three stages: water evaporation (100～180 ℃), volatile matter pyrolysis (205～550 ℃) and inorganic salt decompose (550～900 ℃). Sewage sludge combustion process are divided into four stages: water evaporation (100～180 ℃), volatile matter combustion (180～475 ℃), carbon combustion (475～595 ℃) and inorganic salt decompose (595～900℃). The pyrolysis kinetic parameters of the second stage are as follows: the reaction orders are in the range of 1.5~1.8 and the activation energy is about 48 kJ/mol. The combustion kinetic parameters of the second stage and the third stage are as follows: the reaction orders are in the range of 1.2～1.3 and 1.1～1.2, and the activation energy is about 48 kJ/mol and 176 kJ/mol respectively.