Abstract: In this paper, the Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) is used to analyze the mechanism and stability of the filled embankment on slope with goafs. Three cases are considered. They are (1) goafs with un-treatment (2) goafs with grouting (3) the embankment with grouting plus reinforcing to the slope. The numerical results show that the self-loading of high backfill embankment and traffic live loading can destroy the mechanical equilibrium of the original goafs. The jointing area between the filled and slope surfaces appears shear strain increment concentration, whereas the stress of goafs reaches to a new equilibrium after grouting. The shear strain increment moves down after reinforcing. As a result, the embankment stability increase obviously.