Abstract: OBJECTIVE To study the synthetic process of antiobesity drug lorcaserin hydrochloride(1). METHODS 1 was synthesized form N-allyl-N-2-(4-chlorobenyl)ethyltert-butyl carbamate(3) in a three-step process via one-step intramolecular Friedel-crafts alkylation and deprotection, chiral resolution with L-(+)-tartaric acid, and the final salification. RESULTS In overall yield was 24.7% the purity was 99.9%, and excellent enantioselectivity(ee) >99.8%. The intermediates and target product were confirmed by ¹H NMR, ¹³C NMR and ESI-MS. CONCLUSION This convenient and economical procedure is remarkably applicable for industry.