A single frequency Nd: glass laser with pulse trangimission mode (PTM) Q-switch and resonant reflector (RR) as longitudinal mode selector is described, The spectral, spatial and temporal characteristics of laser emission are measured, Stable output pulses of 5 ns width, up to 0.5mJ energy are obtained. The experimental results are in good agreement with the prediction of theory of the optimally coupled Q-switched laser.