After immersed in hydrochloric acid,sulfuric and acetic acid solution with different concentration,the mass and strength losses ratio of the polymer-modified mortar were measured.The results show that the acid-resistance of the polymer mortar is enhanced.The more the polymer content,the better the corrosion-resisting property.The corrosion resistance of polymer-modified mortar to hydrochloric acid is more improved than that to the two other acids.The mechanism of acid-resistance improvement of polymer mortar is that the polymer film coats the cement hydration products and forms an resilient net which strengthens the cohesion of the mortar.