The co-combustibility of coal and wet sludge (i.e., mechanically dewatered) was investigated through the thermogravimetric analysis. The results showed that the combustion profiles of the blends with a low weight percentage of wet sludge were similar to that of coal alone. Increasing wet sludge in the blend decreased the ignition temperature, increased the burnout temperature, and reduced the average burning velocity. The kinetic analyses with the non-isothermal method indicates that the initial activation energy at a low conversion degree for the blended wet sludge and coal was lower than that for the coal, but the average activation energy depended on the moisture content in the blend. With 3 or 5 wt% of the wet sludge was added into the blend, the small amount of water derived from the wet sludge decreased the activation energy from 89.4 to 35.9 or 64.9 kJ/mol, respectively.