A novel series of D--A bi-alkyne liquid crystal derivatives were designed and synthesized, which had typical D--A structures. The third-order nonlinearities of the compounds were studied by open aperture and closed aperture Z-scan techniques. Both compounds showed typical nonlinear absorptions and refractions, and the third-order nonlinear susceptibilities have been found to be very high in all cases. The significant nonlinear optical response, combined with the possibility to further modify it, by changing the -linking groups and the electron donors or acceptors, suggests that these systems can prove to be important candidates for a variety of photonic/optoelectronic applications.