A method for the preparation of high-purity methiozolin (Formula 1), the method comprising reaction of 4,5-dihydro-5-methyl-3-{(3-methylthiophene-2-yl)-isoxazole-5-yl}methanol represented by Formula 2 below with 2,6-difluorobenzyl chloride (or bromide) represented by Formula 3 below in the presence of an alkali metal salt and a phase transfer catalyst in a mixed solvent system comprising water and an organic solvent at a temperature of 50 to 100° C., followed by crystallizing a concentrate of an isolated organic layer in a mixed solvent comprising water and alcohol or a mixed solvent comprising alcohol and aliphatic hydrocarbon:
