AlFe alloy single crystal film was prepared at 573 K by pulsed laser deposition (PLD) in this work. X-ray diffraction (XRD) and transmission electron diffraction (TED) showed that the space group of the alloy is PM-3M, lattice parameter is a=0.297 nm (just a little greater than that of bcc-Fe, aFe=0.293nm). Crystal lattice of AlFe was the lattice of bcc-Fe with the center Fe atom replaced by the Al atom. First-principles and quasi-harmonic Debye model were employed to study the chemical potential and thermodynamic properties of AlFe alloy. Calculations indicated that the chemical potential (μ) of AlFe is much lower than those of fcc-Al and bcc-Fe, which indicates that AlFe is the only phase formed in the process of film growth. At the same time, AlFe greatly excels the elementary substance of Al and Fe in thermodynamic properties. In the range of 150 K to 1000 K, heat capacity at constant pressure (Cp) of AlFe is much higher than that of Al or Fe, and thermal expansion coefficient (α) of AlFe is lower and more stable.