In order to obtain absorption and emission cross sections spectrum, the relationship between loss coefficient, absorption, emission cross sections and temperature are theoretically analyzed. Spectra for loss, absorption and emission are studied experimentally at various temperatures. The loss spectrum is measured by the cut- back method. The absorption spectrum is attained by the loss spectrum. Then based on absorption spectrum, the emission spectrum via the McCumber relation is received. Experiment shows that the loss coefficient are decreased when the wavelength is less than 1536 nm and increased when the wavelength is larger than 1536 nm as temperature increased.