The invention belongs to the technical field of soil repair, and discloses a method for improving heavy metal polluted acid farmland soil by eggshells. The method comprises the following steps: waste eggshells are cleaned, dried and smashed to obtain eggshell powder; and then, the eggshell powder is uniformly mixed with the heavy metal polluted acid farmland soil to cultivate by above 30 days to obtain improved soil. The eggshells are from agricultural product wastes to change the wastes into wealth, and have the characteristics of low cost, wide application range and no environmental pollution; and the method can effectively increase the soil pH and reduce the activity of heavy metal in the soil, increases the content of effective calcium in the soil, and has important practical significance and practical value on the heavy metal pollution environmental treatment of acid farmland soil around mine areas and the agricultural sustainable development aspect.