Abstract: Lime mediated sludge Was Used as partial replacement for cement raw materials to produce cement. The adding amount of lime mediated sludge ranges from 0 to 30%. The influence of lime mediated sludge on cement performance was investigated. It is shown that adding 15% of lime mediated sludge into cement raw materials can significantly improve the calcining performance, the mineral phase crystal structure and the clinker's morphology, and the cement strength is also remarkably enhanced. The improvement capability of lime mediated sludge gradually declines with the increase of lime mediated sludge. When 30% of lime mediated sludge is added, the properties of the obtained cement are similar to those without adding sludge. Toxicity characteristic leaching test results indicate that after lime mediated sludge addition, heavy metalconcentrations in clinker and cement are higher than those in clinker and cement without lime mediated sludge, while the leaching concentrations are very low, Cu, Zn, Pb, Cr and Ni contents in the leachate are all below 1 mg·L^-1, which canmeet the People's Republic of China Standard GB 5085.3-2007, with no risks of secondary pollution.