The α-NaYF4 single crystals doped with 0.2mol%, 0.5mol%, 1mol%, 2mol% and 3mol% Er3+ ions were fabricated by an improved Bridgman method. The ~1.5µm and ~2.7µm emission properties were investigated in detail through the measured absorption and emission spectra. A Judd–Ofelt analysis of Er3+in α-NaYF4 samples is performed. The Judd–Ofelt parameters are obtained (Ω2=2.71×10−20cm2, Ω4=2.28×10−20cm2, Ω6=0.84×10−20cm2) and the radiative lifetimes of Er3+energy levels and the branching ratios of Er3+transitions are calculated. The calculated maximum emission cross section by McCumber theory for ~1.5µm and ~2.7µm reached 1.35×10−20cm2 and 2.2×10−20cm2, respectively. The gain cross section spectra were calculated based on the absorption and emission cross section spectra. All these spectral properties indicated that this kind of fluoride crystal has potential application as host material for infrared lasers.