The relationships between two-photon absorption (TPA) effect and excited state intramolecular charge transfer (ICT) of p-substituted stilbene-type pyridinium salts have been investigated. Two-photon absorption cross section (δTPA) for all the compounds has been determined by open aperture Z-scanning technique, while two-photon pumped (TPP) up-converted lasing efficiencies (η) and optical limiting behavior have been measured by two-channel energy-meter, pumped by a mode locked Nd: YAG ps laser. Streak camera was used to record two-photon induced fluorescence and the fluorescence lifetimes. The experimental and calculated results have shown that the excited state larger in-tra-molecular charge transfer, in the excited state characterized by the charge density difference between the ground state ( S0) and the first excited state ( S1), has contributed to enhancing TPA cross section and may result in better optical limiting effect. And high TPP up-converted lasing efficiency is related to not only the δTP The relationships between two-photon absorption (TPA) effect and excited state intramolecular charge transfer (ICT) of p-substituted stilbene-type pyridinium salts have been investigated. Two-photon absorption cross section (δTPA) for all the compounds has been determined by open aperture Z-scanning technique, while two-photon pumped (TPP) up-converted lasing efficiencies (η) and optical limiting behavior have been measured by two-channel energy-meter, pumped by a mode locked Nd: YAG ps laser. Streak The experimental and calculated results have shown that the excited state larger in-tra-molecular charge transfer, in the excited state characterized by the charge density difference between the ground state ( S0) and the first excited state (S1), has contributed to enhancing TPA cross section and may result in better optical limiting effect. And high TPP up-converted lasing efficiency is related t o not only the δTP