Abstract: This study focuses on the problem of water slag engineering waste pollution existing in the application of high-pressure water jet breaking treatment technology in the repair construction of concrete buildings. It analyzes the internal design characteristics of the vacuum negative pressure water slag collection and separation equipment structure, improves the sealing and connection performance of the pipeline, reduces the size of the collection and separation equipment, and optimizes the structure of the water slag separation device. A small and highly efficient water sludge collection and separation device combined with water jet equipment has been developed. Experimental research was carried out through on-site repair projects. The results show that when the inflow volume of the new water-sludge separation and collection device is 1.5 m³/h,~3.0 m³/h, the removal efficiency of solid particles reaches more than 78.3%. The use of this equipment can reduce the concentration of solid particles in the wastewater from 208.1 g/m³ to 29.7 g/m³, with a reduction rate of 85.7%. After separation by the equipment, the average moisture content of the waste soil has decreased by 48.2%. The quality of water slag collection and separation has been significantly improved, effectively reducing water slag pollution during construction, as well as problems such as landslides during the storage of construction waste and leakage during transportation. It has excellent safety and environmental protection characteristics and application prospects in high-pressure water jet renovation projects.