Abstract: In testing the staged breakstone-cement filling, a new technique was adopted first in China. Theprocess of the technique is that the natural breakstone and cement slurry are carried form surface filling stationseparatly into underground mixing point, where the cement slurry is spraied on the breakstone to form mixture,then the mixture is filled by LHD. The quality of filling mass directly affects on the strenth of filled mass and itsability of anti-failure caused by blasting vibration, its stability and filling cost. This paper discusses in detail thequality-affecting factors of the filling mass and its quality-ensuring measures.