Cr3+ co-doped Nd:YAG is very useful for the flashlamp or solar pumped laser through Cr3+ ion has broad absorption bands in the visible region and an efficient energy transfer caused from Cr3+ to Nd3+. But the process of the energy transfer is not understood well. It is also a problem that the absorption at near infrared is appeared with changes of Cr3+ to Cr4+. We investigated these problems by measuring the temperature dependence of fluorescence characteristics (lifetime, excitation fluorescence and absorption) and the change after UV irradiation. The excitation fluorescence spectra at 450 K increased because the Cr3+ absorption depended on temperature. The fluorescence lifetime excited at the Cr3+ absorption bands shortened with increase temperature, that is, the energy transfer time will be short. Solarization was appeared in Nd/Cr:YAG ceramics irradiated by KrF excimer laser pulses at 248 nm.