The invention discloses a carboxylic ester of fucosylated glycosaminoglycan (CEFG) with anticoagulation activity, a pharmaceutically acceptable salt thereof, a preparation method of the CEFG and the pharmaceutically acceptable salt thereof, a pharmaceutical composition containing the CEFG or the salt thereof, and application of the pharmaceutical composition in preparation of anticoagulants. The monosaccharides for preparing the CEFG comprise D-glucuronic acid or D-glucuronate (D-GlcU), D-2-deoxy-2-acetyl galactosamine sulfate (D-GalNAcS) and L-fucose sulfate (L-FucS), wherein the molar ratio of D-GlcU to D-GalNAc to L-Fuc to -OSO3<-> is 1:(1+/-0.3):(1+/-0.3):(3.5+/-0.5); the esterification degree of the D-GlcU is not lower than 20%; and the weight average molecular weight of the CEFG is 3000-20000 Da. The glycosylated chondroitin sulfate esterification derivative has strong anticoagulation activity, and can be applied in preparation of drugs for preventing and/or treating thrombotic diseases.