ASE pulses of the 5-stage Nd:Glass rod amplifier system were measured and the temporal profiles were calculated at each stage. The effects of the ASE on the gains were also investigated. In order to determine the pumpig efficiency coefficients of the amplifiers, the results of the small signal gain measurements were employed. By using the coupled rate equations and the boundary conditions, temporal profiles of the ASE signals were obtained. And the temporal profiles were compared with those of the ASE signals which were detected by the photo diode and the fiber bundle located in front of one end surface of each rod. Similar tendencies in the change of the peak power and the pulse width were obtained. The population inversion densities were calculated as a function of position. The inversion densities at the end of each rod were smaller than those at the central regions. Lowering of the small signal gains due to the ASE were calculated. The calculated small signal gains were 99.33\%(at Amp1), 99.33\%(at Amp2), 99.45\%(at Amp3), 99.55\%(at Amp4), and 99.76\%(at Amp5) of the values in the case without ASE, at the charging voltage of 4.5kV.
