After the processes of crushing, screening and grinding, abandoned mortar powder can be used as a mineral admixture to replace cement. Physical-activating, alkali-activating and compound-activating have been used to stimulate the activity of abandoned mortar power. To get the mechanical properties and microstructure, compressive strength, flexural strength, XRD, TG-DTA and SEM were used. The results show that: Mechanical grinding and activator can greatly improve the activity of mortar power. Stimulating effect of compound activator was better than signal activator and it could promote further hydration of cement. The mortar which is stimulated by compound activator had higher strength than mortar by single activator. It can be seen from micro-test that the mortar with compound activator had more ettringite and other hydration products, and with compact structure.