We report a new synthesis method of liposomes with tunable size as well as enhanced monodispersity of the size distribution and high throughput in a contraction–expansion array (CEA) microchannel. Lipid vesicles were generated in the CEA microchannel by injecting lipids in isopropyl alcohol as a sample flow and phosphate buffered saline as a buffer flow, leading to spontaneous formation of liposomes. Generated lipid vesicles from the CEA microchannel showed narrower size distribution than ones from the linear microchannel. The throughput of the lipid generation in the CEA microchannel was ten times higher than previous works.