Abstract: Sludge co-processing in cement kiln, compared to other disposal way, which avoids of incomplete disposal and second pollution, is an ideal way for sludge disposal. Before the sludge is fed into kiln, a drying pretreatment is necessary, which demands large amount of heat and electric energy resulting in huge operation cost. The water content of sludge is firstly reduced down to 55% which avoids of viscous zone by the deep dewatering pretreatment of chemical conditioning and physical press filter, then dried by the waste gas, this treatment process significantly reduces the sludge dewatering cost. The progress in chemical conditioning of sludge was summarized in this paper and the difference of deep dewatering as well as regular dewatering are analyzed in order to provide a reference for the adoption of sludge chemical conditioning and deep dewatering.