The Fe2+∶ZnSe crystal has been prepared by thermal diffusion doping technique. The iron ions doping concentration that was measured by Secondary Ion Mass Spectrometry (SIMS) in the crystal sample reaches 1.27×1018cm-3. The optical absorption spectrum of the Fe2+∶ZnSe crystal was analyzed. The results show that a 2.90 μm laser is used to pump the Fe2+∶ZnSe crystal at room temperature,67 mW average power of mid-infrared laser output at center wavelength 4.45 μm is obtained.