The invention relates to a method for preparation of an emulsion explosive by using waste explosives. The method comprises the following process steps: preparation of water phase liquid, preparation of a compound oil phase, emulsification, cooling, sensitization and charging. A key point of the invention lies in that waste emulsion explosives are utilized; and the waste emulsion explosives refer to chemical bubble-sensitive emulsion explosives which suffer demulsification, crystallization, hardening and the like and lose detonator sensitivity and detonation capacity. In the method, the waste emulsion explosives are used in the preparation of the water phase liquid. According to the invention, low temperature, environmental protection and no pollution of three wastes (waste gas, waste water and industrial residue) are realized, according with developmental requirements; and except packages of explosive cartridges, the explosives are totally recovered, and a high recovery rate is obtained.