Abstract: Mirtazapine was prepared by a seven-step reaction,namely nucleophilic ring-opening reaction,chlorination,cyclization,uncleophilic substitution,hydrolysis,reduction and cyclization from styrene oxide and N-methylethanolamine as the starting materials,with overall yield of 22.6%.The structure of mirtazpine was confirmed by()~1H-NMR(H~1-nuclear magnetic resonance) and MS(mass spectrum),and the purity was 99.79% by HPLC.