The invention relates to a method for preparing trifluridine (Viroptic). The method comprises the following main steps: by using uridine (a compound shown in a formula II) as a starting raw material,sequentially carrying out the steps such as esterification and halogenating reaction of hydroxyl, reduction reaction, trifluoromethylation reaction and protective group removal reaction so as to obtain a target. The method provided by the invention has the advantages that the use of expensive raw materials and the use of reagents with high toxicity and capability of polluting an environment are avoided and reaction conditions required in all steps are mild; therefore, the invention provides a preparation method of trifluridine with environmental protection property, security property and a commercial preparation value.