Abstract: Aiming at the problems of large demand and high cost of fly ash in traditional coal mine paste filling materials, the mechanical properties and acid resistance of limestone powder instead of part of fly ash as admixture of paste filling materials were studied. The optimal ratio of limestone powder paste filling material and its effect on acid resistance were determined by mixed orthogonal test and limit test. The results show that the strength of filling body is the best when the paste ratio is 25%-50% of limestone powder replacement, 25-38 μm of limestone powder fineness, 190 kg/m³ of cement content and 82% of mass fraction. In the acid mine water, the limestone powder paste has both hydration reaction and decomposition reaction, and the compressive strength increases first and then decreases. Its acid resistance is positively correlated with the fineness of limestone powder and negatively correlated with the substitution amount of limestone powder. When the substitution amount of limestone powder is 25% and the fineness of limestone powder is 25 μm, the paste has better acid corrosion resistance.