The invention relates to an asphalt cold-patching additive which is prepared from the following components in parts by weight: 100 parts of light diesel oil, 15 to 20 parts of vinyl siloxane, 60 to 80 parts of unsaturated acid, 5 to 8 parts of a wetting agent, 0.2 to 1 part of initiator mother liquid and 0.015 to 0.8 part of chain terminator mother liquid. The asphalt additive has the beneficial effects that the cold patch asphalt additive can enable matrix asphalt to be proper in viscosity, so that the matrix asphalt can be quickly mixed with aggregates uniformly in a normal temperature state instead of preheating the asphalt or the aggregates; furthermore, the asphalt cold-patching additive is relatively high in water-resistant stripping performance; compared with existing thermal mixing of asphalt, cold patching has the advantage of saving a large amount of construction equipment required on the site during repairing of a pavement and is quick and convenient.