Carbazole-core multi-branched chromophores 9-ethyl- 3, 6-bis ( 2- { 4- [ 5- (4-tert-butyl-phenyl) - [ 1, 3, 4 ] oxadiazol-2-yl ] - phenyl }-vinyl) -carbazole(3) and 9-ethyl-3-( 2- {4-[ 5-(4-tert-butyl- phenyl) -[ 1, 3, 4 ] oxadiazol-2-yl ] -phenyl }-vinyl ) -carbazole ( 2 ) are synthesized through Wittig reaction and characterized by nuclear magnetic resonance(NMR)and infrared(IR). The two- photon absorption properties of chromophores are investigated. These chromophores exhibit large two-photon absorption crosssections and strong blue two-photon excited fluorescence. The cooperative enhancement of two-photon absorption(TPA) in the multi-branched structures is observed. This enhancement is partly attributed to the electronic coupling between the branches. The electronic push-pull structures in the arm and their cooperative effects help the extended charge transfer for TPA.