The invention relates to a cement-based material of carbon nano tube fiber and a preparation method thereof, in particular to a toughened cement-based material and a preparation method thereof. The invention solves the problems of relatively low anti-bending and anti-breaking intensity and toughness of the existing fiber toughened cement-based material. The material is produced by a fiber dispersant, an organic solvent, carbon fibers, carbon nano tubes, deionized water, a superplasticizer, a polymer emulsion, mineral admixture and cement. The preparation method of the invention is as follows: the fiber dispersant is added into mixed slurry of the cement and stirred; the primarily mixed slurry is fed into a high shearing colloid mill for shearing at high speed for 5 to 30min; the evenly stirred slurry is poured into a test mould which is moved to a vacuum drying case for pressure reducing and bubble-removing and heated for evaporation of the solvent for 0.5 to 3 hours; after 24 hours, and the material is obtained after tearing the mould and maintained in water at room temperature. The fracture energy GF and the fracture toughness of the material obtained by using the method of the invention respectively are 106.3N question mark m and 0.998Mpa/m<-1/2>, which are respectively 112.6 percent and 33.1 percent higher than the fracture energy and the fracture toughness of the existing fiber toughened cement-based material.