The invention discloses a synthetic method of 5-trifluoromethyl uracil prepared under simple and convenient conditions. The synthetic method is characterized in that starting from uracil and trifluoroiodomethane, after alkali is added, the 5-trifluoromethyl uracil is efficiently obtained under the irradiation of visible light. Some of products obtained are listed drug molecules or important pharmaceutical intermediates. The synthetic method has the benefits that the uracil and the trifluoroiodomethane which are cheap and easy to obtain are used as raw materials; in the reaction process, only the illumination is required, and the cheap alkali is added without the use of a catalyst; during the mass production, a solvent can be recovered through a vacuum distillation method; the synthetic method is green, economic and efficient in the whole production process and has very significant advantages compared with an existing production process.