As the key index of stealth performance of aircraft skin, the emissivity is an important means to evaluate the comprehensive stealth performance of the aircraft. The spectral emissivity measurement method of infrared stealth coatings was introduced, and the corresponding calibration device at ambient temperature was established. A Fourier transform spectrometer based on Michelson interference theory was designed to realized the spectral splitting. The sample chamber with gold-plated integrating sphere was used to realize the vertical incidence and diffuse receiving of the signal, and the accurate measurement for spectral emissivity of stealthy coating was realized. A traceability method using diffuse reflection films as the reference standard was proposed, which realized the traceability of calibration device. Finally, the spectral emissivity of brass and other samples was measured by using the proposed calibration device, and the measurement results with a spectral range of 3 μm~12 μm were obtained. The measurement uncertainty of spectral emissivity is better than 3.2% (k=2).