Abstract: In order to improve the impermeability of ordinary mortar, an experimental study was proposed to combine organic polymers with inorganic minerals and incorporate organic silicon to endow ordinary mortar with excellent impermeability performance. Through the determination and analysis of the compressive strength, folding strength, impermeability strength and water absorption rate of waterproof mortar, the high performance polymer modified waterproof mortar was obtained. The results showed that: (1) The film structure, formed by redispersing latex powder in cement mortar, would significantly reduce the compressive strength and increase the impermeability strength. The appropriate mixing amount should be 3% of the cement quality; (2) The volcanic ash activity of the parakaolin could undergo a secondary reaction with the hydration product. However, attention should be paid to the relationship between admixture and mechanical properties, the amount of dosage should not be greater than 6%; (3) The silicone hydropathy group, formed by polysiloxane in mortar, could give waterproof mortar good hydrophobic, further improve the impermeability strength and reduce the water absorption rate, the comprehensive performance was optimal at 0.5% mixture; (4) The polymer-modified waterproof mortar had good mechanical properties, the impermeability intensity was increased from the initial 1.0 MPa to 2.3 MPa, the water absorption was decreased from 7.7% to 5.2%, all the properties were far beyond the requirements of the national specifications for polymer waterproof mortar. The research results could provide reference for the popularization, use and modification of waterproof mortar.