Three-photon-absorption-induced frequency up-conversion fluorescence emission has been observed in a solution of 4-2-(7-(4-amido styrene)-9,9-di(2-ethyl hexyl)-9H-fluorene-2-) ethylene) aniline (BASF) in N,N-dimethylformamide(DMF), pumped with 38ps Q-switched 1064nm laser pulses. The spectral peak of the observed fluorescence emission is located in the 456—775nm range, and the intensity dependence of the visible emission on the IR excitation obeys the cubic law. At higher solute concentration and moderate IR excitation intensity levels, obvious optical limitation behavior has been observed due to three-photon-absorption. The measured nonlinear absorption coefficient and the molecular three-photon-absorption cross section are 4.34×10-20cm3/Ｗ2 and 2.4×10-39cm6/Ｗ2, respectively.