The nonlinear optical properties of newly synthesized triaryl boron-based A-pi-A and triaryl nitrogen-based D-pi-D compounds have been studied with hybrid density functional theory. The generalized few-state model is employed to calculate two-photon absorption cross sections of the compounds. It is found that boron-based A-pi-A compounds have large two-photon absorption cross sections. Moreover, the length of pi center has larger effect on the one- and two-photon absorption properties of boron-based A-pi-A compounds than those of nitrogen-based D-pi-D compounds. The numerical simulation shows that boron-based A-pi-A compounds have similar performance as nitrogen-based D-pi-D analogues in regard to nonlinear optical properties. Boron-based A-pi-A compounds are promising candidates for large two-photon absorption materials. The theoretical results are in good agreement with the available experimental measurements. (c) 2006 Elsevier B.V. All rights reserved.