In this paper, the structure of glasses in Li2O(LiCl)2B2O3-Al2O3 system, particularly the influence of Al2O3, is investigated by Raman spectra. For Li2O-B2O3 glasses, with increasing Li2O content, triangular BO3 units change into BO4 tetrahedra and borate groups containing more BO4 are formed. When Li2O content is greater than 35 mol% the metaborate groups begin to form. By replacing B2O3 with Al2O3, the Al3+ ions introduced in glasses take the four-coordination, and AlO4 tetrahedra replace BO4 tetrahedra under the condition of existing sufficient Li2O. However, when Al2O3/Li2O ratio is close to or even greater than unity, part of Al3+ ions are no more in the four-coordination. The experiment also indicates that Raman spectra only depends upon the O/B/Al ratio, showing that the LiCI molecules introduced into the glass are dissociated by glass network. These results can be used to interprete the variations of ionic conductivity with composition.