Abstract: This paper used single factor experiment to study the influence of drying characteristics on drying temperature and wind speed and slices thickness. Dynamic law of moisture with time was analyzed and hot air thin- layer drying dynamics model was established. On the basis of single factor experiments, the drying operation conditions of red pigment extraction were optimized by orthogonal experiment. The results showed that the effects for thin-layer drying rate of carmine radish from high to low was slice thickness >temperature>wind speed. Hot air thin-layer drying of carmine radish was analyzed to meet the Page equation dynamic model with the comparison of three kinds of mathematical models. The optimal red pigment extraction rate was as much as 3.12% with drying temperature of 60 ℃ and wind speed of 0.8 m/s and slice thickness of 6 mm.