The improvement of sludge rheological properties is very important for large-scale resource utilization of high-moisture sludge.The effects of adding calcium desulphurizer such as limestone and calcium carbide slag on the rheological properties of sludge were system⁃atically studied. The effects of limestone or calcium carbide slag ratio, particle size and shear time on the rheological characteristics ofsludge were investigated by using a rotating rheometer. The results show that the apparent viscosity and shear stress of the mixture increasewith the proportion of desulfurizer limestone or calcium carbide slag, and the rheological properties of the mixture change significantlywhen the proportion of desulfurizer is greater than 15%. The fluid changes from a yield pseudoplastic fluid to a Bingham fluid when theproportion of limestone is more than 15%. The apparent viscosity of the mixed paste decreases with the increase of shear time at the sameshear rate, showing the phenomenon of shear thinning. The smaller the proportion of two desulfurizers is, the more obvious the shearthinning phenomenon is, and the apparent viscosity decreasing trend is more significant at the lower shear rate of 35 s-1. The analysis ofdesulfurizer mixed paste with the same proportion at the same shear rate is found that the apparent viscosity of the mixed paste with theparticle size of 0-0.075 mm is greater, indicating that the smaller the particle size of the desulfurizer is, the more significant the effect onthe rheological properties of the mixture is. The moisture content of the mixed paste can be reduced by pumping the sludge with calcium based desulfurizer, and the desulfurization function can be played in the furnace after pumping into the furnace. The optimal proportion ofdesulfurizer is 15% - 20%. This study provides theoretical guidance for sludge combustion utilization and optimal design of pumpingscheme in circulating fluidized bed.