Through crushing, screening and grinding, abandoned mortar power can be used as a mineral admixture to replace cement. Physical-activated, alkali-activated and composite-activated have been researched on activity of abandoned mortar power. Mechanical properties and microstructure were tested by compressive strength, flexural strength, XRD, TG-DSC-DTC and SEM. The results show that: Mechanical grinding and activator can significantly improve the activity of mortar power. Stimulating effect of single activator was not obvious. Composite activator has better effect than signal activator and it can promote further hydration of cement. The mortar which is stimulated by composited activator had higher strength than mortar with single activator. It can be seen from micro-test, the mortar with composite activator had more ettringite and other hydration products, having compact structure.