The effects of the multi-photon resonance ionization (MPRI) and the charge-resonance enhanced ionization (CREI) on the molecular high-order harmonic generation (MHHG) from H-2(+) have been investigated by using the chirped pulses. It is found that the MHHG only comes from the MPRI in the shorter pulse duration. As the pulse duration increases, both the MPRI and the CREI contribute to the MHHG. But the MPRI plays the main role in the generations of the above-threshold harmonics and the CREI mainly contributes to the below-threshold harmonics. With the introductions of the up-chirped and the down-chirped pulses, the contributions of the MHHG from the CREI and the MPRI can be enhanced, respectively. Finally, the isotopic investigation (e.g. T-2(+)) shows that due to the slower nuclear motion of the heavy nuclei, the contributions of MHHG from the CERI can be suppressed in the heavy nuclei. (C) 2017 Elsevier B.V. All rights reserved.