Slices of tiegun yam were dried at different temperature and thickness without any chemical preservatives added. To dry the slices with constant temperature, optical fiber was used to detect the center temperature of the slices. As the material, fresh tiegun yam was dried by single factor experiment. To evaluate the drying parameters, polysaccharide was extracted by soxhlet extraction and phenol sulfuric acid colorimetry was used to determine polysaccharide e yield of the samples. Besides, weight was online recorded with microwave drying system. Moreover, the sample color was measured with controlling different temperature of material and constant thickness of 5 mm, the highest of the yield of polysaccharide was retained from temperature of material 50 ℃, with the maximum whiteness value, but the drying time was longest. With different thickness of the material when the temperature was 60 ℃, the highest of the yield of polysaccharide was retained from material thickness 5 mm. In general, microwave drying temperature 60 ℃ and the material thickness 5 mm after harvest will retain higher yield polysaccharide higher yield , better color and costs less time.