Hanbury-Brown-Twiss (HBT) results of the nucleon-nucleon correlation function have been presented for the nuclear reactions with neutron-rich projectiles using an event-generator, i.e. the isospin-dependent quantum molecular dynamics model. A good agreement of our calculation for the two-halo-neutron correlation function of 11 Li with the experimental data has been reached. In addition, we explore the relationship between the singleneutron separation energy and the strength of the HBT results. It is feasible to investigate the exotic structure of neutron-rich nuclei with the HBT method.