High molecular weight functional polyurethanes bearing large pi electron conjugated chromophoric pendants with different conjugation bridge structure, poly(1a), poly(1b), and poly(1e), were synthesized and characterized by FTIR, H-1 NMR and UV-vis absorption spectra. Their optical properties were evaluated by optical limiting and nonlinear optical analyses. The results show that these polymers possess good optical limiting and large nonlinear optical properties, which are attributed to the long D-pi-A conjugated pi electron structure of the NLO-chromophoric segment. Poly(la) with C=C double bond as pi electron conjugation bridge shows better optical limiting property than poly(1b) and poly(1c) with C=N or N=N double bond as conjugation bridge structure under the same linear transmittance, while poly(le) with N=N double bond as pi electron conjugation bridge of the NLO-chromophoric segment is superior on nonlinear optical properties to poly(la) and poly(1b) with C=C and C=N double bonds as pi electron conjugation bridge structure, respectively. (c) 2006 Elsevier Ltd. All rights reserved.