We investigate the influence of gate-source/drain (G-S/D) misalignment on the performance of bulk fin field effect transistors (FinFETs) through the three-dimensional (3D) full band Monte Carlo simulator. Several scattering mechanisms, such as acoustic and optical phonon scattering, ionized impurity scattering, impact ionization scattering and surface roughness scattering are considered in our simulator. The influence of G-S/D overlap and underlap on the on-states performance and carrier transport of bulk FinFETs are mainly discussed in our work. Our results show that the on-states currents increase with the increment of G-D/S overlap length and the positions of a potential barrier and average electron energy maximum vary with the G-D/S overlap length. The carrier transport phenomena in bulk FinFETs are due to the effect of scattering and the electric field in the overlap/underlap regime.