Abstract: Alkaline phosphorous slag cementitious material in which sodium silicate and sodium hydroxide were chosen as activators was studied. At the same time, the pore structure and its hydration were analyzed. The experiment results show that sodium silicate is better than sodium hydroxide as activator, and the strength of 28 day is about 20MPa higher than that of NaOH. The total porosity is only 2.65%, so it is of advantange for improving the durability of alkaline phosphorous slag cement.