The experiment was made on acid slag powder as cementitious material, which was inspired based on the best recipes for 28 days. Analysis was made on the influence law of mass concentration, cement-sand ratio, dosage of water reducing agent and stirring time on the mortar fluidity, water loss rate, shrinkage and compressive strength; and according to the cement-sand ratio, comparison was made on the slurry performance of cement and slag powder cementitious material. Finally, the appropriate proportion was selected for orthogonal experiment to optimize various factors combination to achieve optimal comprehensive performance of the mortar.