The improvement of landscaping soil fertility using organic wastes could be a feasible practice to avoid contaminants from entering the food chain but at the risk of polluting the soil, surface water, and groundwater. Currently, millions of tons of sewage sludge compost is used to improve the nutrient contents in the soil each year in China. To study the mobility of heavy metals, N, P, and EDCs in the soil, an experiment was conducted at a field site for over two years to study the application of sewage sludge compost to degraded grassland soils in Beijing. The grassland soil was amended with 6, 12, and 18 t/ha of compost sludge. The results indicate that the concentrations of Cu, Zn, and Cr in the 0–20 cm surface soil layer increased with an increase in the dosage of the compost sewage sludge, while the concentrations of Ni, Cd, As, Hg, and Pb did not change significantly. In the 0–100 cm soil profile, the concentrations of the DTPA-extractable Zn and Ni were significantly higher than that of the control, while the concentrations of the DTPA-extractable Ni, Cd, As, and Hg did not vary significantly. The concentrations of the DTPA-extractable Cu, Pb, and Ni were reduced as the depth of soil increased. The concentrations of heavy metals, such as Cd and Cr, in the surface run-off during the rainy season had exceeded the China surface water environmental quality standards (III). The estradiol toxic equivalency was below 10 and 0.1 ng/g in compost sludge and grassland soil, respectively. The soil phosphatase and catalase increased initially and then decreased with the increasing dosage of the compost sludge. The application of sewage sludge compost increased the content of phosphorus in the 0–20 cm surface soil layer by 100–200%, and the ammonia content was increased by 16–100%; the nitrate content was, however, lowered by approximately 35%. The concentrations of nitrogen and phosphorus in the surface run-off of content met the surface water environmental quality standards, while the content of heavy metals Cd and Cr did not. Therefore, the application of compost sludge should be avoided in rainy seasons to reduce the environmental risks of contamination from heavy metals.