4-(8-Chlor-5,6-dihydro-11H-benzo[5,6]cyclohepta[1,2-b]pyridine-11-ylidene)-1-piperi-dine carboxylic acid ethyl ester (Loratadine) was prepared from ammonia and methyl acrylate through Michael addition, Dieckmann cyclization, decarboxylation, ethoxy carbonylation and McMurry reaction. The conditon of McMurry reaction was conducted under ultrasound irradiation, and technological parameters involved in McMurry reation were optimized. Structures of the title compound and the intermediates were confirmed by 1HNMR. The results show that n(8-chloro-10,11-dihydro-4-aza-5H-dibenzo[a,d]cyclohepten-5-one):n(N-ethoxycarbonyl-4-piperidone):n(TiCl4):n(Zn)= 1:1.2:4:6.8 reacted under 25kHz and 67℃（under reflux）for 30min to give the intermediate in 88.5%, and the total yield of target compound（Loratadine） was 57.8%.