The dynamic changes of germination percentage, germination potential, thousand-seed weight, antioxidase activity in Desmodium styracifolium seeds with different storage time were tested, and electrical conductivity, contents of soluble sugar, soluble protein, starch in seed leach liquor were also determined in order to reveal the mechanism of seed deterioration. The results as the following. (1) The germination percentage, germination potential and thousand-seed weight of D. styracifolium seeds declined, while the seed coat color darkened with the extension of storage time. (2) The activities of superoxide dismutase (SOD) and peroxidase (POD) decreased with the prolongation of storage period. The SOD activity declined fastest in 1,095-1,185 d of storage, while the POD activity declined significantly in 365-395 d of storage. (3) The electrical conductivity and the contents of soluble sugar, starch in seed leach liquor increased, while the content of soluble protein declined with the extension of storage time. (4) Correlation analysis indicated that the germination percentage, germination potential and thousand-seed weight of D. styracifolium seeds have a significantly positive correlation with SOD and POD activity, while have a significantly negative correlation with the electrical conductivity, contents of soluble sugar and starch. It can be concluded that during the storage of D. styracifolium seeds, physiological and biochemical changes including decrease in antioxidase activity, rise in electrical conductivity, degradation effluent of soluble sugar and starch, degradation of soluble protein were the main factors leading to the seed deterioration.