SrAl2O4: Ln (Ln = Ce3+, Pr3+, Tb3+) nanocrystals have been synthesized by the combustion method. The results of XRD indicated that the resulting SrAl2O4: Ln (Ln = Ce3+, Pr3+, Tb3+) nanocrystals have a reduced and distorted monoclinic lattice compared with bulk materials. The spectral properties are measured, and it is found that the excitation peaks of 5d energy levels red shift in nanocrystals in contrast to that in bulk crystals. The mechanism of spectra and energy changes is investigated. The order of the degree of red shift for nano SrAl2O4: Ln (Ln = Ce3+, Pr3+, Tb3+) crystals is Pr3+ > Ce3+ > Tb3+, which is in good agreement with our predicted results.