Abstract In this Letter, we extend the theoretical model [Chem. Phys. Lett. 280 (1997) 66] by including the effect of dopant ions to describe doped C60-based nanotube. The substitute doping effect on the third-order optical non-linearities, characterized by the second-order hyperpolarizabilities γ, of zigzag nanotube is studied by substituting one carbon atom of zigzag nanotube with a boron or nitrogen atom. It is found that the substitute doping by boron or nitrogen atom increases greatly the γ values of zigzag nanotube. The theoretical results are significant for photonic applications of boron- or nitrogen-doped carbon nanotubes [Chem. Phys. Lett. 300 (1999) 695].