Abstract: Some experiments were conducted in a thermogravimetric analyzer to investigate the thermal behaviors of sludge,pulverized coal and their blended fuels. By analyzing the change of ignition temperature (Ti ),burnout temper- ature (Tb ) and comprehensive combustibility index ( S),the effects of different additives on the co-combustion of sludge- pulverized coal were studied and the mechanism of catalytic combustion was discussed. Results indicate that adding sludge can decrease the Ti of pulverized coal and accelerate its pyrolysis and combustion which improves the combustion performance of pulverized coal. However,when the mixing ratio of sludge is more than 10% ,the maximum weight loss rate of blended samples decreases significantly and Tb increases. The comprehensive combustion perform- ance for blended fuels is deteriorated. Calcium oxide and sodium carbonate contribute to the devolatilization and com- bustion of volatile matter,thereby drive the subsequent combustion of fixed carbon. Therefore,the two additives im- prove the burning rate and comprehensive combustion performance of blended fuels,and shorten the burning time. Manganese dioxide and iron oxide have no significant catalysis on blended fuels and reduce its maximum combustion rate. Meanwhile,the kinetic analysis shows that adding calcium oxide and sodium carbonate can reduce the apparent activation energy of combustion system,while adding manganese dioxide and iron oxide have no obvious effect on that of blended fuels.