Two novel fluorene_based derivatives 9_(7_(9H_carbazol_9_yl)_9, 9_bis (2_ethylhexyl)_9H_fluorene_2_yl)_9H_carbazole (abbreviated as DCZF) and 2, 7_bis (4_metho xystyryl)_9, 9_bis (2_ethylhexyl)_9H_fluorene (abbreviated as BMOSF) were synthe sized and their linear absorption and one_photon fluorescence spectra were measu red. We used a 38ps, 1064nm Nd:YAG pulsed laser operating at 10 Hz to invest igate the three_photon absorption (3PA) properties of the two compounds. The re sults show that the linear absorption band of the two compounds is from 270—420 nm with absorption peaks at 330 and 380nm. The fluorescence bands were locat ed in the blue_violet region with the peak wavelengths of 369 and 442 nm, and s mall Stokes shifts were observed. Nonlinear absorption coefficients γ deriv ed from 3PA fitting curves are 678 and 592×10-20 cm3/ W2, respectively. Large optical power limiting induced by 3PA has also been demonstr ated for both dyes. When the incident irradiances reach 8 and 6 GW/cm2, t he limiting nonlinear transmissions of DCZF and BMOSF can reach to 30% and 45%, respectively.