Abstract:In the "winter wheat‖early spring maize/summer maize" cropping system, the vertical distribution and its change of root quantity and activity of the intercropped summer maize were studied The main results are as follows: ① The maximum rooting depth of the intercropped summer maize was about 160 cm and the root quantity in 120~160 cm soil layer continued to increase till the late waxmature stage ② From top to deep soil layers, the vertical distribution of root weight and root weight density shaped like a "T", and 0~20 cm, 20~80 cm, 80~120 cm and 120~160 cm could be classified, respectively, as high, mid, lower and thin root density layers The root density in the soil layers of 0~20 cm, 20~40 cm, and 40~80 cm reached its maximum, respectively, at flowering stage, and decreased afterwards; while that in the soil layers of 80~120 cm and 120~160 cm reached its maximum at milking or late waxmature stage The total (0~160 cm) root quantity and its density reached its peak at milking stage ③ Contrary to the quantity distribution, root activity (TTC reducing capacity) shaped like "⊥" from top to deep soil Peak root activities at jointing, male tetrad, milking, and late waxmature stage occurred in 20~40 cm, 80~120 cm, 120~160 cm soil layer, ie, the highest activity point moved deeper with the advance of growing stages The average root activity of 0~160 cm reached its top point at male tetrad stage ④ The root TTC reducing quantity and its density shaped like "T" on the vertical soil profile, and 0~20 cm, 20~120 cm, and 120~160 cm were classified as high, mid, and lower density layers respectively With the advance of growing stages, the root TTC reducing quantity and its density reached top at flowering stage in 0~120 cm, at milking stage in 120~160 cm The total (0~160 cm) root TTC reducing quantity and its density reached top at flowering stage