The mixed filler of solidified mud and sand provides an ideal solution for the resourceful disposal of wasted engineering mud，and the compression characteristics of filling engineering are closely related to the strength characteristics and particle breakage characteristics of mixed fillers.This study conducted large size compression tests on mixed fillers with different particle gradations and established a discrete element method （DEM） model that incorporated particle breakage for the side-limited compression tests of solidified mud-sand mixed fillers.The changes in the compression modulus of the mixed fillers and the amount of solidified soil particle breakage during compaction were investigated.The study placed a special focus on analyzing the impact of factors such as the solidified mud mixing ratio and the initial void ratio on the compression properties and the stress-strain relationship of the mixed fillers.It also demonstrated the feasibility of using mixed fillers in filling engineering.The results show that under compacted conditions，the compressibility of the solidified mud-sand mixed fillers is positively correlated with the mixing ratio of clay particles，but negatively correlated with the strength of mud particles.The addition of a certain amount of solidified mud particles can effectively reduce the compressibility of loose sand at low stress levels.However，the compressibility of the mixed fillers slightly improves due to the breakage of mud particles at high stress levels.In the compression process，the degree of particle breakage in the mixed filler increases with the increase in mud mixing ratio and sand initial void ratio，and the final breakage rate tends to approach 80% at the end of compression.