The optical limiting effect of fullerence C_(60)/C_(70) was investigated by passing the second harmonic generation (530 nm) of a YAG laser through the solution of C_(60)/C_(70) in toluene. The output energy of the solution increased linearly with the increment of the input energy at very low energy, while, as the input energy increased continuously, the output energy increased slowly and finally was limited to a certain value. The influence of the triplet state quenched and concentration of the solution on the optical limiting effect was also investigated.