Abstract:As a by-product of municipal sewage treatment, municipal sludge contains a lot of organic matter and rich nutrients such as nitrogen, phosphorus and potassium, but also contains a variety of heavy metals. After mining, the mine soil is poor and barren, therefore, a large amount of guest soil and timely fertilization are needed in ecological restoration. This article investigates the amount of sludge products added to the guest soil by detecting the chemical composition of the guest soil, calculation, experiment, and expert argumentation. Based on the effective control of heavy metal content, the goal of utilizing and treating the urban sludge to save soil costs is achieved, which is also verified through engineering practice. The results show that it is feasible to use sludge products in improving the soil quality of the abandoned mine land. The application of sludge products not only meets the soil pollution requirements, but also enhances soil fertility to a certain extent, with good ecological restoration. The innovation is that sludge products can replace part of the substrate materials for mine restoration, and generally save about 10%-30% of soil cost. In addition, the fertilizer cost can also be reduced. Moreover, the sludge products containing about 50% water reduces the water requirement of vegetation growth and the cost of labor and equipment for irrigation during the maintenance process. Therefore, this study can be used as a reference for similar engineering practice in the future.