Abstract: After the roof-contacted filling，the ability of controlling the overburden was directly affected by the deformation value of backfill under the complicated stress conditions.In order to reveal the mechanics mechanism of the backfill in service process in deep mining，the deformation performance of backfill under complicated stress conditions must be understood deeply.Combined with engineering practice and in base of laboratory tests，the consolidation deformation characteristics of different curing age side-confined backfill were studied in this paper，and the compression rules of different curing age backfill were revealed.The constitutive relations of backfill in the process of side-confined consolidation were discussed.And the whole process of backfill under side-confined consolidation from elastic deformation to elastic-plastic deformation was analyzed.The conclusions can provide a scientific basis for deep mining design and safety management.