In order to establish a more perfect evaluation system for dryness effect of Atractylodis Rhizoma, determine the main dry parts of Atractylodis Rhizoma，and further define the mechanism of stir-baked Atractylodis Rhizoma in reducing the dryness. The healthy rats were given with different doses of water extract and volatile oil of raw Atractylodis Rhizoma and stir-baked Atractylodis Rhizoma for 21 days. Based on the theory of the dry-dry and dryness-induced Yin deficiency, the amount of drinking water, tissue morphology of submandibular glands, urine volume and the expression of aquaporin 2 (AQP2) in the kidneys, as well as blood rheology, ratio of cAMP/cGMP in serum and the content of Na⁺-K⁺-ATP enzyme were selected as the evaluation indexes. The results indicated that the rats with high dose volatile oil from raw Atractylodis Rhizoma had a significant increase in the amount of drinking water, urine volume, blood viscosity, ratio of cAMP/cGMP and content of Na⁺-K⁺-ATP enzyme in the serum（<0.05）as compared with the soybean oil group; meanwhile, atrophy of submandibular acinar gland was obvious，and the expression of aquaporin 2 was reduced significantly（<0.05）. There were significant differences between volatile oil high dose group of raw Atractylodis Rhizoma and volatile oil high dose group of stir-baked Atractylodis Rhizoma. There was no significant difference between the water extract groups of raw and stir-baked Atractylodis Rhizoma and the saline group. A comprehensive evaluation system for the dryness effect of Atractylodis Rhizoma was established. It was confirmed that the volatile oil part was the main dry part of Atractylodis Rhizoma. It revealed that the mechanism of dryness effect of Atractylodis Rhizoma was not only related to the decrease of the total content of the volatile oil, but also may be related to the transformation of dryness components in the volatile oil. It provides references for the study of material basis of Atractylodis Rhizoma dryness, provides an experimental basis for the clinical application of Atractylodis Rhizoma, further clarifies the mechanism of stir-baked Atractylodis Rhizoma in reducing the dryness, and provides thoughts for the evaluation of other dry traditional Chinese medicines.