Preparation method of uridine-5'-monophosphate disodium

The invention discloses a preparation method of uridine-5'-monophosphate disodium. The method comprises the following steps: (1) mixing cytidine monophosphate (CMP) or sodium salt, sodium nitrite and deionized water, dropwise adding acid and/or acid anhydride, continuously reacting for 0-6 hours after completing dropwise adding to obtain reaction solution 1; (2) if residual quantity of CMP is lower than 1%, adjusting the pH value of the reaction solution 1 to 6.4-7.2 to obtain reaction solution 2; (3) mixing the reaction solution 2 and 95v/v% of ethyl alcohol, crystallizing and filtering to obtain a uridine-5'-monophosphate disodium crude product; (4) mixing the uridine-5'-monophosphate disodium crude product and water, and adjusting the pH value to 7.0-8.5 to obtain reaction solution 3; and (5) mixing the reaction solution 3 and an organic solvent, recrystalizing and filtering to obtain the uridine-5'-monophosphate disodium.