The synthetic procedure of antidepressant mirtazapine [i.e., 1,2,3,4,10,14b-hexahydro-2-methylpyrazino[2,1-a]pyrido[2,3-c][2]benzazepine] was improved. Using 2-chloronicotinonitrile and 1-methyl-3-phenylpiperazine as the starting materials, mirtazapine was obtained by a synthetic sequence involving an alkylation, hydrolysis, reduction and intramol. Friedel-Crafts alkylation. The structure of mirtazapine was confirmed by elemental anal., IR, NMR, 13C-NMR, MS. Compared with the synthetic process reported in the literature, the above-mentioned optimized synthetic procedure was simple and suitable for industrial production with lower cost and higher yield. The overall yield was improved from 46% to 60%.