Abstract: As a paste filling material for coal mines, ammonia-containing fly ash will not only affect the filling environment, but also affect the performance of the filling paste, which will affect the safety of coal mine filling. This experiment analyzes the ammonia source of fly ash, tests the ammonia content of fly ash, and conducts experimental research and mechanism analysis on the influence of ammonia fly ash on the performance of the filling body. The results show that the ammonia content of fly ash is 0.16%, which exceeds the normal standard, which leads to the release of irritating gas during the filling process, which affects the construction environment of the goaf. The ammonia content of fly ash will lead to the prolongation of the filling paste and the strength. It decreases, and as the ammonia content increases, the effect on the paste performance is more serious.