The invention discloses a preparation method for a powdery zinc carbonate rust inhibitor, and belongs to the field of chemical building materials. The doped powdery zinc carbonate rust inhibitor is prepared by using zinc carbonate, calcium phosphate, sodium nitrite, sodium molybdate and lignin sulfonate as raw materials and through the methods of crushing and mixing the raw materials. The preparation method is simple in process, low in production cost and good in product quality. The powdery zinc carbonate rust inhibitor is simple in usage method and is usually added to the concrete by using a dry mixing method, with an addition amount of 3%-4% in the concrete for common industrial and civil buildings and an addition amount of 6%-8% in the concrete for coastal engineering. After the powdery zinc carbonate rust inhibitor is used, the concrete has a good rust-inhibiting effect. Besides, the powdery zinc carbonate rust inhibitor is low in cost and small in toxicity, and has no influence on physical health of operation staffs who are engaged in concrete constructions.