The invention provides a grading method of an on-site cold-recycling mixture of foamed asphalt. The on-site cold-recycling mixture of the foamed asphalt is prepared from the foamed asphalt, an old road surface milling material, aggregate, cement and water; the mixing amount of new aggregate is determined according to the thickness of a cold-recycling structure layer and the milling thickness of anold road surface, and meanwhile, the graduation of the foamed asphalt, crude aggregate, fine aggregate, the cement and the water in the new aggregate is controlled, so that the on-site cold-recyclingmixture of the foamed asphalt, which is provided by the invention, has excellent pavement performance. Meanwhile, the invention further provides the on-site cold-recycling mixture of the foamed asphalt, which is prepared by the grading method, and application of the on-site cold-recycling mixture of the foamed asphalt in old road maintenance and reconstruction.