With the rapid development of urbanization construction, a large amount of building waste is generated from the demolition of old buildings, and a significant quantity of construction debris is produced during construction projects. These wastes urgently need to be disposed of and utilized. This project aims to conserve energy and promote waste utilization, using waste to manage waste, by proposing the resourceful use of effective components from discarded clay bricks and construction slag to render them harmless and achieve high-value resource utilization. The project intends to develop a new type of cementitious material based on solid waste, utilizing discarded clay bricks and slag; further utilize it to treat construction slag for modification, improving the fluidity and hardening properties of the slag, addressing issues such as low fluidity, high density, and high bearing capacity of backfill soil in construction projects. At the same time, this reduces the dry shrinkage value of the backfill soil to ensure its fullness after backfilling, shortens the hardening time of fluidized backfill soil, etc.; based on the aforementioned technical research, determine the modified slag backfilling construction process technical scheme. The realization of high-value resource utilization and technological transformation of the results for building waste clay bricks and construction slag can generate significant social, economic, and environmental benefits.