Resonant effect is found in femtosecond laser ablating Pr–Nd glass. When processed with resonant wavelength of 807 nm, resonant ablation efficiency (RAE) with a single pulse can be improved by 45.22%. Furthermore, RAE closely relates to laser intensity. For resonant ablation, RAE is increased significantly when laser intensity <0.556×1014W/cm2 at which multiphoton ionization dominates, while it fades away when laser intensity >0.556×1014W/cm2 at which tunnel ionization dominates. Besides, it is also found that the ablation depth increases along with the wavelength rise when multiphoton ionization dominates, while the change rule is inversed when tunnel ionization dominates.