An improved synthetic process of fludarabine phosphate(1)was developed.Commercially available fludarabine was subjected to a nucleophilic substitution with triethyl phosphate.Subsequently,the target compound 1 was obtained through hydrolysis of triethyl phosphate on exposure to phosphorus oxychloride condition with an overall yield of 81%and a purity of 99.91%.The optimized process bearing mild reaction conditions,simple operation and stable process had been tested by process verification,and was suitable for industrial production.