Firstly, 1-(4-Fluorobenzyl)-2-chloro-1H-benzoimidazole was synthesized from 4-fluoroben-chloride and 2-chloro-1H-benzimidazole.Secondly, the obtained 1-(4-Fluorobenzyl)-2-chloro-1H-benzoimidazole ammonolysis reacted with methylamine piperidine to give 1-[1-(4-fluoro-benzyl) methyl-1H-benzimidazol-2-yl]-N-methyl-4-piperidinamine.Finally, mizolastine was synthesized from 1-[1-(4-fluoro-benzyl) methyl-1H-benzimidazol-2-yl]-N-methyl-4-piperidinamine and 2-methylthio-4-pyrimidone.The overall yield was about 54%.