Abstract: On the experimental basis of the absorption spectrum,excited spectrum and emission spectrum of Er3+-doped Mg-Al spinel crystal,we fined that there are two main absorption lines of wavelength 380nm and 522nm in its absorption spectrum,three strong fluorescence lines of 528nm, 536nm and 549nm and other fluorescence lines in green range.Based on these results,we can calculate the spectrum parameters,such as resonator strength relative to energy transition,transition probabilities of self irradiation, irradiation life and integrated irradiation section.So,we can employ Er:MA spinel crystal to build a novel laser operating at green band or 1.50μm.