The measurement of light spectrum with wavelength from 200 nm to 1000 nm emitted from solid surface of Al which is excited by slow highly charged ions 126Xeq+ (6≤q≤30) is reported. The result shows that the characteristic spectral lines from transitions between complex configurations of atoms and ions can be effectively excited by the impact of highly charged ions on a solid surface even though the ionic beam is very weak. The relative intensity of those spectra can be enhanced sharply and greatly if the stripped charge q of incident ions (q) is beyond a critical value (q=26 for Al). According to the classic over-barrier modek, electrons captured and transferred play key roles in interaction between highly charged ions and solid surfaces if the kinetic energy of the incident ions is small (～1 keV/u). The ability of ions capturing electrons can be intensified by increasing charged states of the incident ions, therefore, the light spectra intensity of excited particles can be enhanced significantly.