In this study, we tested the physiological responses of Leymus mollis (Trin.) leaves and roots to sand burial on the Yantai coast of China to understand the biochemical and physiological adaptive mechanisms of this species to sand burial. Based on the height of L. mollis (about 40 cm) four levels of sand burial treatments were set up: no-sand burial (control), light sand burial (1/4 plant height), moderate sand burial (1/2 plant height), and severe sand burial (3/4 plant height). After 6 days of sand burial, samples were taken from the leaves and roots of plants in each treatment. Changes in malonaldehyde (MDA) content, an osmotic regulator, in addition to antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity, were measured in the leaves above and below the sand and in the roots at various depths. Plants under light and moderate sand-burial grew fast until they protruded from the sand, becoming taller than control plants after 6 days. Compared to the control, the average MDA content increased in whole leaves under light and moderate sand burial, but and decreased in leaves subject to severe sand burial. In all three sand burial treatments, SOD activity and proline content increased in whole leaves, whereas CAT activity and soluble sugar and soluble protein contents decreased. In all three burial treatments, MDA, proline, and soluble protein content increased in leaves above the sand, along with SOD and CAT activity, especially in the top section of the leaves. In contrast, MDA, soluble sugar, and soluble protein content, in addition to CAT activity, decreased in the leaves beneath the sand. This resulted in significant differences in MDA, proline, soluble sugar, and soluble protein content, in addition to SOD and CAT activity, between leaves above and below the sand (P< 0.05). Compared to above ground leaves, underground roots had lower MDA and soluble protein content, in addition to lower SOD and CAT activity, but higher POD activity and soluble sugar content. After 6 days of sand burial, there was a small change in MDA and soluble sugar content, with soluble sugar content and CAT, POD, and SOD content slightly decreasing in the roots. On the same plant, leaves above ground had significantly higher (P<0.05) MDA and soluble protein content, along with higher CAT and SOD activity, than the underground roots. This result indicates that sand burial had a greater effect on the aboveground structures (branches and leaves) above ground compared to the underground structures. Sand-burial caused the accumulation of oxygen free radicals in the cells, which induced lipid peroxidation and activated the antioxidant enzymatic protection system to scavenge oxygen free radicals and maintain the metabolic balance of oxygen free radicals. This action also promoted osmotic adjustments to maintain the balance of water metabolism and provide energy and nutrition. Thus, under sand burial, it may be important to enhance cell antioxidant and osmotic adjustment capacity rapidly to maintain the balance of oxygen free radical metabolism and metabolic water balance, a key physiological regulation strategy for L. mollis for sand burial adaptation. Moreover, the root system was not affected by the different levels of sand burial, and continued to sustain lower levels of lipid peroxidation, allowing the roots to maintain normal functions of water suction and transportation, and to support the fast growth of leaves out of the sand.