The invention discloses a foamed asphalt cold-recycling lime-fly-ash crush stone mixture and a preparation method thereof. The mixture comprises a recycled old material, cement, foamed asphalt and water. The mixture and the preparation method have the advantages that a foamed asphalt recycling lime-fly-ash crush stone base layer technology is adopted, so that a plenty of aggregate materials needed for paving a new semi-rigid base layer are saved, the land stacking treatment of the lime-fly-ash crush stone old material is not needed, the land is saved, and the cultivated land is protected; the crack resistance, water stability performance and anti-washing performance of the base layer are improved; the lime-fly-ash crush stone base layer maintenance problem can be effectively solved, and the resource cyclic utilization is promoted; through the foamed asphalt recycling lime-fly-ash crush stone base layer, the damage to the asphalt pavement is reduced, the pavement driving quality is ensured, and the effect of prolonging the service life of the asphalt pavement is achieved.