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 intercropped summer maize were studied The main results are as follows: ① The maximum rooting depth of the intercropped summer maize was about 160 cm and the root quantity in 120～160 cm soil layer continued to increase till the late waxmature 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 waxmature 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 waxmature stage occurred in 20～40 cm, 80～120 cm, 120～160 cm soil layer, ie, 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