Judd-Ofelt (J-O)theory is the classical theory which is used to semiquantitative study 4f energy levels transitions’s spectroscopic properties of rare-earth ions doped materials. Because many approximations and assumptions were involved in standard J-O theory, there are some exceptional behaviors when it is used for special earth ions such as Pr3+. Pr3+-, Tm3+-doped fluorogallate glasses were fabricated and the absorption spectrum of these glasses were studied. According to standard and modified Judd-Oflet theories, the different J-O intensity parameters Ωλ and oscillator strengths of those glasses have been calculated. The results show the “hypersensitive transitions” play the important role in exceptional behaviors of J-O theory calculation. When the corresponding odd reduced matrix element of “hypersensitive transitions” is added, the Ωλ of Pr3+ in fluorogallate glass obtained from modified J-O theory are more reliable than other approaches; for the experimental oscillator strengths of Tm3+, there is also a better fit by the modified J-O theory than other calculated ones.