This paper reports the experiments of chemi-cal and physical activation of γ-C_2S and their results.Chemi-cal activation is that the addition of active substances to γ-C_2Scan promote its 3 days hydrated ratio to 20% and 7 days to26-31%.Physical activation,on the other hand,by irradiat-ing γ-C_2S with energetic ray,can promote its 3 dsays hydrat-ed ratio to 29%.Our experiments illustrate the mechanisms ofγ-C_2S chemical activation and physical activation.The for-mer is the formation of the insoluble by combination of theadded active substances with Ca(OH)_2,which is dissolvedfrom γ-C_2S,breaks the γ-C_2S dissolving-precipitating equilib-rium and promotes its hydration process.As a result,CSHhydrate is formed more rapidly.The latter is that the elasticcollision between the enegetic particles,which eater the γ-C_2S,and cause some atoms in lattice to deviate from their normalpositions and become interstitial atoms,and forms vacancy de-fects simultaneously.As crystal defect density increases,freeenerg