Leymus mollis (Trin.) Hara growing on coastal dunes at different zones from the high tide in Yantai, China, was used as a study material. The contents of soluble sugar, starch, and cellulose in the leaves and various sections of the root of L. mollis were measured during late fall and winter when the temperature decreased to below 0℃, and in the spring when the temperatures started rising, in order to understand the correlation between changes of carbohydrate levels and environmental heterogeneity and to elucidate the role of physiological plasticity in L. mollis in the adaptation to wind and salt. The results showed that L. mollis grown on dunes near to the high tide line (10 m), characterized by higher salt concentration in the soil, higher moisture level, higher wind speed, and lower temperatures had stronger and thicker rhizomes and shoots, foliage grew closer to the groud, and sprouting commenced later in spring. In contrast, L. mollis growing away from the high tide line (50 m), in the zone characterized by lower soil salinity, lower wind speed, and higher temperature, had thinner roots, slender branches and leaves, and sprouting occurred in early spring. These results indicate that morphological plasticity of L. mollis growing on coastal dunes was associated with environmental heterogeneity. With the drop of temperature in late fall, the non-structural carbohydrates in the leaves of L. mollis were transported to the roots, buds, and rhizome, stored in these organs as a carbohydrate pool. As the soluble sugars were removed from the roots and rhizomes to the buds, the starch content decreased and cellulose content increased in the roots and the rhizome. A difference was detected in the carbohydrate transfer and conversion in L. mollis growing on coastal dunes at different distance from the high tide. L. mollis at the zone near to the high tide line (10 m) transferred the non-structural carbohydrates from the leaves to the roots earlier in the winter, stored more non-structural carbohydrates in the roots, and sprouted later in the spring. However, they accumulated more cellulose in the leaves, which was correlated with higher resistance to low temperature and sea wind. L. mollis growing 50 m away from the high tide line had a longer living cycle extending into late fall, they transferred less non-structural carbohydrates from the leaves to the roots in winter, stored less non-structural carbohydrates in the roots, and earlier sprouting root in spring. These results indicate that at 50m the content of nonstructural carbohydrates in leaves and roots was highly associated with plant's rapid growth and adaptation to lower salinity and wind speed. The results suggested that the physiological plasticity of carbohydrate metabolism in L. mollis growing on coastal dunes at different distance from the high tide line played an important role in its adaptation to heterogeneous environment, resulting in morphological plasticity, maintaining high ecological amplitude, and formation of resistance to salt and sea wind.