NOVELTY - Synthesizing ceftriaxone sodium comprises adding 7-amino-3-(((2,5-dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4-trizin-3-yl)-thio)methyl)-cephalosporanic acid, dimethyl carbonate, boron trifluoride and organic acid into a four necked flask, uniformly mixing, stirring the mixture, cooling the stirred mixture at 10-12 degrees C, drying the cooled mixture, adding triazine and 7-aminocephalosporanic acid to the dried mixture, holding the mixture, adding cold water, EDTA-disodium salt and sodium hydrosulfite to the mixture at 13 degrees C, filtering the mixture, washing the filter cake and vacuum drying.    USE - The method is useful for synthesizing ceftriaxone sodium (claimed).    ADVANTAGE - The method is capable of simply and easily synthesizing ceftriaxone sodium with high purity of more than 99.6% and yield of more than 94% under mild reaction conditions and reduced pollution and cost.    DETAILED DESCRIPTION - Synthesizing ceftriaxone sodium comprises adding 7-amino-3-(((2,5-dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4-trizin-3-yl)-thio)methyl)-cephalosporanic acid, dimethyl carbonate, boron trifluoride and organic acid into a four necked flask, uniformly mixing, quickly stirring the mixture, cooling the stirred mixture at 10-12 degrees C, drying the cooled mixture, adding triazine and less than 1% of 7-aminocephalosporanic acid to the dried mixture, holding the mixture at 10-12 degrees C for 20-30 minutes, adding cold water, EDTA-disodium salt and sodium hydrosulfite to the mixture at 13 degrees C, adding diluted ammonium hydroxide to the mixture, regulating pH of 2.3-2.6, separating white solid at 5-10 degrees C, filtering the mixture using a filter to obtain a filter cake, washing the filter cake using water and ethanol, vacuum drying, adding binary solvent, dichloromethane and ethanol to the dried mixture, cooling the mixture at -10 degrees C, stirring the mixture, dropping tetramethylguanidine to the stirred mixture, holding the mixture at -5 degrees C to -10 degrees C, adding active ester to the mixture at -5 degrees C to -10 degrees C for 4 hours, raising the temperature to 10-15 degrees C, adding water to the mixture, stirring the mixture, standing and layering the mixture, removing organic phase and water phase, adding sodium salt to the mixture, dropping acetone to the mixture, separating crystal, slowly stirring the mixture, continuously dropping acetone until there is no crystal for 2 hours, filtering the mixture using a filter to obtain a filter cake, washing the filter cake using acetone, and vacuum drying.