Backfilling mining can protect the environment. In order to scientifically determine the strength of cemented tailings backfill, it conducts lateral confinement and consolidation test for grading consolidated tailings backfill with concentration 70%, cement-sand ratio of 1:10, 14, 28, 56d of curing period respectively under different stresses, to demolds consolidated filling test block and conduct mechanics experiment under uniaxial compressive condition, and then get stress-strain curve after lateral confinement consolidating, analyze its breaking rule, based on which to apply elastic and plastic damage theory to establish damage constitutive model for filling compression failure after consolidating lateral confinement. Theoretical curve got by the constitutive equation has better goodness fit with that of test curve, which indicates that model established can describe mechanical properties and damage characteristics of filling body after consolidating lateral confinement, providing reference for deeply exploit and filling design to some extent.