In order to to improve the pozzolanic activity of the pulverized powder from the high temperature sintering slag of surface treatment sludge and construction residue, the effect and mechanism of Ca(OH)₂ on mechanical properties and heavy metal leaching of Portland cement-based materials were studied, and the microstructure characteristics of the materials were analyzed by XRD, SEM, BET, TG and other microscopic testing techniques. The results show that when Ca(OH)₂ content is 0.6%~0.8% of the total mass of ground powder cement-based materials, the mechanical properties of cement-based materials mixed with grinding powder are better. At 60 days, the flexural strength and compressive strength increased by 11.0% and 7.8%, respectively. Microscopic test results show that a small amount of Ca(OH)₂ can not only increase the specific surface area of ground powder cement-based materials’ hardened slurry, but also increase the number of hydration products, and improve the structural compactness of hardened slurry. However, when the content of Ca(OH)₂ exceeds 0.8% of the total mass of cement-based hardened slurry, it has a negative effect on the structure and properties of cement-based materials. It is also found that the addition of Ca(OH)₂ can reduce the leaching concentration of harmful heavy metals in cement-based materials with the addition of the ground powder. The leaching rates of Cu, Ni and Zn were 17.5%, 13.0% and 40.8% lower than those of blank group. It can ensure that the leaching values of harmful heavy metals Cu, Ni, Zn and Cr in cement-based materials mixed with grinding powder are lower than the leaching concentration limits specified in the Technical Specification for Coprocessing of Solid Waste in Cement Kiln (GB/T 30760—2014).