Abstract: In order to understand the relation between the harmonic spectra efficiency of H₂⁺ and its isotope molecule with laser wavelength, the relation between the harmonic intensity of H₂⁺ and D₂⁺ with the wavelength in the range of 600nm~1600nm was theoretically studied by solving 2-D time-dependent Schrdinger equation. It is shown that the intensity of harmonic spectrum is decreased as the wavelength increases. In shorter wavelength region, the decrease rate of harmonic intensity of H₂⁺ is greater than that of D₂⁺. In longer wavelength region, the decrease rate of harmonic intensity of H₂⁺ is smaller than that of D₂⁺. Furthermore, driven by lower laser intensity, the harmonic yield of H₂⁺ is always higher than that of D₂⁺. Driven by stronger laser intensity, the harmonic yield of H₂⁺ is lower than that of D₂⁺ in shorter wavelength region; while, it is higher than that of D₂⁺ in longer wavelength region. Theoretical analyses show that the extension of nuclear distance and charge resonance enhanced ionization play the important role in the change of harmonic yield of H₂⁺ and D₂⁺. The results are helpful for molecular harmonic control.