The absorption and thermal radiation characteristics of the silicon carbide gratings within the wavelength range from 10 μm to 14 μm are studied and analyzed by the rigorous coupled wave analysis (RCWA) method. Influences of different physical parameters (period, depth, filling factor and incident angle) on the spectral properties are discussed in detail. The conclusions are as follows: Under TM-polarization, the period, grating depth, grating width and incidence have a significant effect on the absorption/emission spectral. With the increasing of the period and the grating depth, the absorption peak/emission peak will redshift and the peak will decrease. While the filling factor (f) decreases, the absorption peak appears within the Restrahlen band, and the smaller the f is, the larger the absorption peak is. When the incident angle is increased, the peak value of absorption/emission spectrum decreases. The conclusions of this study can also be extended to other polar crystal materials.