Abstract:  The effect of drying condition and particle size of sewage sludge on its co-slurry ability with Shenfu coal was investigated with naphthalene condensate as dispersant. The results show that the concentration of coal-water-sewage (CWS) slurry is greatly improved when the sewage sludge was dried and milled before preparation of the slurry. It is beneficial to raise the concentration of CWS slurry with increasing drying temperature which has a great effect on particle size distribution. With increase in drying temperature the surface mean diameter of milled sewage sludge falls and the apparent viscosity of CWS slurry decreases. When the drying temperature is above 105℃, there is no obvious change of grindability of the dried sewage sludge and the apparent viscosity of CWS slurry. The smaller particles of sewage sludge improve the packing efficiency of coal to a certain extent, resulting in the apparent viscosity of CWS slurry decrease.