Abstract：With the promotion and popularization of ready mixed mortar，admixture which can improve the performance of mortar has been widely used. Admixtures would affect the performance of building mortar. Here, the effect of four kinds of mortar admixture on the performance of mortars is investigated, and the results show that the admixture content has a great effect on the performance of the mortar. When the admixture content is 0.025%～0.075%, the compressive strength and tensile strength of mortars increase effectively, and the shrinkage and freezing resistance are improved as well. The mortar admixture with multi-component shows more prominent technical and economic characteristics.