Jinong 15 and Jinong 24 were divided into 5 canopies by plant height—lower, lower-middle, middle, up- per-middle and upper—for analyzing 100-seed weight, seed vigor, changes in antioxidant enzyme activities and MDA content with germination for 7 d in different canopies of soybean cotyledon. Soybean 100-seed weight increased slightly and then decreased gradually with increasing canopy, with the upper ones being the lightest. The germination rate and germination potential were higher in the low and lower-middle heights, and their vigor indexes were significantly higher than in the upper-middle and upper heights. The stem diameter of seed germination seedlings were significantly greater in the lower and lower-middle heights than in the upper-middle and upper heights. The antioxidant enzyme activities of the cotyledon during seed germination were higher in the lower and lower-middle heights than the upper height, but the MDA content was less than in the upper height. The low and lower-middle part was the best canopy because the seed vigor was high, seedlings were robust, and cotyledon metabolism was vigorous.