Lasers in the 3-5 μm waveband have many important scientific and military applications such as remote sensing, environmental protection, medical treatment, communication and infrared countermeasures. Fe2+:ZnSe crystal has become one of the most promising materials to generate laser in this region due to its advantages in material and optical properties. The characteristics of a polycrystalline ZnSe sample, which diffusion-doped with Fe2+ ions at a concentration of 3×1019/cm3, were investigated. The diameter and the thickness of the sample were 10 mm and 1 mm, respectively. The output characteristics of the Fe2+:ZnSe laser, which was excited by a non-chain electric-discharge pulsed HF laser, were studied at room temperature. A mid-infrared laser with the maximum output energy of 78.8 mJ at a center wavelength of 4 295 nm was obtained. The efficiency respecting to the absorbed pump energy was 27.7% and the slope efficiency was as high as 28.8%. The Fe2+:ZnSe laser was pumped at a small angle(3°) with respect to the optical axis of the laser cavity instead of orthogonal-pump. It solved the problems that a HF laser and a Fe2+:ZnSe laser are both in the mid-infrared band.