In this paper, Fe2+∶ZnSe laser crystal with a size of 22 mm×4 mm was obtained by double temperature zone thermal diffusion doping method using CVD ZnSe wafer as the host material and FeSe powder as the dopant. SIMS show that iron ion concentration on the surface of the crystal sample is 3.43×1018 cm-3, and the valence state of iron in the crystal sample was analyzed by XPS. The transmission spectra of Fe2+∶ZnSe laser crystals were tested by UV/Vis/NIR spectrophotometer and Fourier transform infrared spectrometer, presenting that there is an obvious Fe2+ absorption peak at 3.0 μm with the peak transmittance of 5.5%. Fe2+∶ZnSe crystal with a size of 10 mm×10 mm×4 mm was pumped by Cr, Er∶YAG laser with a wavelength of 2.93 μm at 77 K, obtaining a mid-infrared laser output of 191 mJ and a center wavelength of 4.04 μm with the light-to-light conversion efficiency of 13.84%.