Provided is a process for preparing Voriconazole represented by Chemical Formula 1. More particularly, the process for preparing Voriconazole of Chemical Formula 1 includes: carrying out the Reformatsky-type coupling reaction between a ketone derivative of Chemical Formula 4 and a pyrimidine derivative of Chemical Formula 5 to obtain a compound of Chemical Formula 3; reacting the substituents halo and oxysulfonyl with a hydrogen donor to obtain racemic Voriconazole of Chemical Formula 2; and carrying out optical isolation of the racemic Voriconazole by adding an adequate optically active acid thereto to obtain Voriconazole having high optical purity with high cost-efficiency and high yield.