The impact of activation additives on the macro-physical properties of gypsum-based cementing composite was studied with comparative experiments. The hydration products were characterized by using scanning electronic microscopy and X-ray diffraction.The results have indicated that the addition of 2wt% coagulant and alkaline activator enhances the macro-physical properties of the composite. The major hydration products in the material are calcium sulfate dehydrate, calcium silicate hydrate gel(C-S-H), ettringite (AFt), and xonotlite（Ca6Si6O17(OH)2）. Moreover, a skeleton of calcium sulfate dehydrate and ettringite with high content of C-S-H gel gives better physical properties to the composite.