The invention belongs to the technical field of a coal mine, and particularly relates to a coal mine early strength type low-cost filling material and a preparation method thereof. The filling material is prepared from water, a bonding material, an excitant, an auxiliary excitant and a mixture of tunneling waste rock and furnace bottom ash, wherein the water accounts for 21 to 23 percent of the filling material; the bonding material is a mixture of portland cement clinker, fly ash and water quenched ore slag, and accounts for 15.2 to 19.5 percent of the filling material; the excitant accounts for 0.5 to 0.9 percent of the bonding material; the auxiliary excitant is a mixture of sulphoaluminate cement clinker and desulfurized gypsum, and accounts for 2.5 percent of the bonding material; the balance is the mixture of the tunneling waste rock and the furnace bottom ash. The coal mine early strength type low-cost filling material has the advantages that the early strength is high; the flowing performance is good; the bleeding rate is low; the requirements of most coal mines on the performance of the filling material can be met; solid waste and mine waste water account for 93 percent or more of the total mass of materials in the filling material, so that the cost of the filling material is reduced; the waste is sufficiently utilized; good economic benefits and environment benefits are realized.