A low-molecular-weight fucosylated glycosaminoglycan (aTFG) containing 2,5-anhydrated talose, alditol, glycosylamine or N-substituted glycosylamine monosaccharide composition thereof, preparation method thereof, pharmaceutical compositions containing the aTFG, and use thereof for preventing and/or treating thrombotic diseases are provided. The aTFG has potent anticoagulant activity targeting at intrinsic coagulation factor Xase, and inhibiting thrombogenesis, and therefore can be used as drugs for preventing and/or treating cardiovascular and cerebrovascular diseases.