In order to reveal the optical properties of carrot slices during infrared drying, the appearance quality of carrot slices during infrared drying was analyzed. The content of soluble solids in pulp and cortex of carrot slices, the texture of pulp and cortex of carrot slices during drying were determined. The surface reflectance spectrum, absorption spectrum and ultrastructure were analyzed. It was found that the energy consumption per unit of material had linear negative correlation with the 5th power of absolute temperature. The browning occurred when the moisture content was decreased to 20%, and the browning degree of the infrared drying material was higher than that of the hot air drying material at the same temperature. When it was dried at 60℃ for 1.5h, the hardness of the upper surface of the pulp was higher than that of the lower surface, and the hardness of the lower surface of the cortex was higher than that of the upper surface, which indicated that the moisture content of the upper surface of the cortex was lower than that of the lower surface, and the moisture content of the upper surface of the pulp was higher than that of the lower surface. The spectral curve of 350~2500nm showed that the reflectance of cortex was higher than that of medulla in any wave band, and the difference was more obvious in the short wave band. Scanning electron microscope images showed that the diameter of the pores in the medulla was larger and the tortuosity was lower than that in the cortex, which was conducive to the transmission of infrared rays to the deep layer. Transmission electron microscope images showed that the number of particles in cortex was more than that in medulla. According to the scattering theory, short wave light had Mie scattering, and long wave light had Rayleigh scattering in the cortex, short wave light had Rayleigh scattering, and there was no Mie scattering in the medulla. The reflectance of the cross section with porous surface was lower than that of the longitudinal section with dense surface.