Based on one-dimensional photonic crystals, a narrowband quasi-coherent infrared thermal emitter with the central wavelength corresponding to the infrared absorption peak of CO2 was designed. Its central wavelength, emissivity and full width at half maximum (FWHM) are 4.23 μm, 〉 99% and 49.9nm, respectively. Transfer matrix method (TMM) and finite difference time domain method (FDTD) were used to analyze and simulate this infrared thermal emitter respectively. The results obtained by theory calculations and simulated spectral property are consistent. So the feasibility of this kind of narrowband thermal emitter is verified.