Temperature dependences of multiphonon relaxation rates for 4F3/2 states in Nd3+-glasses were determined by measuring fluorescence intensity and lifetime in the range of 300-600 K. According to the theory of multiphonon relaxation and vibrational spectrum we made a theoretical fitting of curves. Multiphonone processes of 4F3/2 states have been investigated in five Nd3+-glasses. The phonon energy and number involved in the process were determined and the relation between matrix property and phonon relaxation was analysed. Further examination of multiphonon relaxation theory was conducted in this material.