Nuclear quantum effects strongly modify the electron dynamics in intense laser fields, which has recently triggered extensive investigations into high-order harmonic generation. Nevertheless, there is limited theoretical research regarding the nuclear effect at various laser deflection angles. This work examines the high-order harmonic generation by \(\mathrm{H_2^+}\) at different laser deflection angles, comparing the harmonic features under the non-Born-Oppenheimer approximation (NBOA) with the fixed-nuclei approximation. Under the NBOA, it is seen that the harmonic intensity along the molecule axis diminishes as the deflection angle increases, while the interference modulation stays relatively mild. Furthermore, the time-frequency spectra of emissions at various moments are examined, indicating that the weak modulation results from the suppression of the extended trajectory. As the deflection angle increases, the expansion of the internuclear distance diminishes. While the multi-track effect influences interference, nuclear motion impacts nucleus return time and ionization rate, alters harmonic intensity, and exerts a restraining effect on harmonics emitted.
