The In1-xAlxSb epitaxial layers of p+-p+-n-n+ barrier structure were grown on the InSb(100) substrate by molecular beam epitaxy. The crystal quality and Al composition of the material were measured and characterized by X-ray diffraction. The full width at half maximum of the InAlSb epitaxial layer was 0.05°, indicating good performance monocrystalline epitaxial material. The Al content of 2.5% was calculated according to Bragg′s formula and Vegard′s law. When the InAlSb material was fabricated as an infrared detector diode and the spectral response curve was measured at 77 K to 210 K, it was found that the cutoff wavelength of the detector increased from 4.48 μm at 77 K to 4.95 μm at 210 K. By fitting the Varshni relation of In0.975Al0.025Sb with the experimental data of bandgap, the values of Eg(0), α and β are 0.238 6 eV, 2.87×10-4 eV/K and 166.9 K, respectively. After the I-V test, the dark current density reached as low as 1.09×10-5 A/cm-2 and the resistance area product is 1.40×104 ?赘cm2 at 110 K, -0.1 V bias, which is equivalent to the performance of InSb detector at 77 K. Besides, the influence of the temperature on different types of dark current was analyzed, and the transition temperature between the diffusion current and G-R current was 120 K.