This paper reports the spectra and the excited energy transfer in phosphate glass doped with Nd3+ and Yb3+. The transfer rates are determined experimentally, at different tempcralures. We confirme that the mechanism of energy transfer is a process in which the energy is transferred from 4F3/2(Nd3+) to 2F5/2(Yb3+) and at the same time a single phonon is emitted. The energy back transfer process from Yb3+ to Nd3+ may occur in two possible ways, one is the process 2F5/2(Yb3+)→4F3/2(Nd3+) which is accompanied by the absorption of a single phonon, and the other is the process 2F5/2(Yb3+)→4I15/2(Nd3+), being accompanied by emission of 4 phonons. Therefore Yb3+→Nd3+ transfer rate depends strongly upon the temperature. At room temperature, the transfer time from Nd3+ to Yb3+ and from Yb to Nd are 197μs and 13ms respectively. The efficiency of energy transfer is 47% for Nd3+→Yb3+ and 8% for Yb3+→ Nd3+.