The key intermediate of voriconazole, 5-fluoro-6-ethyl-4-hydroxy-pyrimidine was synthesized by a "One pot" ammoniated and cyclization reaction with α-fluoro-ethyl propionyl as raw material. The optimal reaction conditions is: sodium methoxid, ammonia stirred in methanol at room temperature for 5 hours, then added carboxamide; stirred under reflux for another 5 hours; the over all yield of is 63%.