The　effect　of　cyclic　loading　on　the　macro-　and　micromechanical　behaviours　of　breakable　granular　materials　was　investigated　via　DEM.　Breakable　particle　models　composed　of　Voronoi　cells　with　realistic　shapes　were　con-structed.　A　series　of　confined　cyclic　loading　tests　were　performed　at　different　loading　amplitudes.　The　macro-scopic　deformation　behaviours　were　investigated　in　terms　of　the　cumulative　plastic　strain　and　dynamic　resilience　modulus.　Then,　particle　breakage　characteristics,　including　the　extent　of　particle　breakage,　crack　orientation　distribution,　breakage　pattern　and　correlation　between　the　particle　breakage　and　energy　input,　were　explored.　Furthermore,　micromechanical　results,　including　the　coordination　number,　sliding　contact　and　contact　orien-tation　anisotropy,　were　examined.　It　is　found　that　both　particle　breakage　and　cumulative　plastic　strain　increase　rapidly　in　the　early　stage　of　loading.　In　the　stable　state,　both　showed　an　S-shaped　increase　with　increasing　loading　amplitude.　This　study　highlights　that　particle　breakage　is　one　of　the　main　sources　of　permanent　deformation