Four D-π-A push-pull type charge transfer molecules were designed basing on the relationship between two-photon absorption and the structure. AM1 method was used to calculate the three-order polarizabilities of the four molecules and the molecule CFM (2-(3-cyano-(3-(4-(dimethyl-amino)styryl)- 5,5-dimethylcyclohex-2-enylidene)methyl)-5,5-dimethylfuran-2-ylidene)malononitrile) was selected out. TCF (2-(3-cyano-4,5,5-trimethylfuran-2-ylidene)malononitrile) used as electronic accepter, N,N-dimethyl- aniline moiety was used as electronic donor, isophorone (3,5,5-trimethylcyclohex-2-enone) as conjugate bridge. CFM was synthesized by Knoevenagel reaction under mild conditions between lively methylene of TCF and ketone. The three-order nonlinear optical property of CFM was got with experiment methods. Using a 800 nm 150 femtosecond Ti:sapphire laser, the CFMs two-photon absorption (2PA) cross-sections reach 104. 29 GM (GM＝10^－50 cm⁴•s•photon^－1) in DMF and 78.22 GM in CH₂Cl₂ which obtained by nonlinear transmission method. The CFM has the property of two-photon absorption and optical power limiting.

Key words: three-order polarizability, Knoevenagel reaction, two-photon absorption, push-pull type molecule