Abstract: Selecting one presently popularized winter wheat cultivar (Zhengmai 9023)  and  two cultivars (Abo and Fengchan 3) introduced in the 1950s and 1960s in Huang-Huai Plain as test materials, and by using minirhizotron technique, this paper studied the live root length, root diameter distribution, and net root growth rate of the cultivars. Fine roots with a diameter from 0.05 mm to 0.25 mm occupied the majority of the whole root system, and the fine roots with a diameter less than 0.5 mm accounted for 98% of the live root length. The average root diameter varied with plant growth, the variation range being 0.15-0.22 mm, and no significant difference was observed among the cultivars. The live root length was significantly positively correlated root number, suggesting that root number was the main factor for the increase of live root length. The most vigorous growth period of the roots was from reviving to jointing stage, and Abo and Fengchan 3 had a longer period increased root vitality, as compared with Zhengmai 9023. For Zhengmai 9023, its fine roots with a diameter more than 0.1 mm had an increasing proportion after jointing stage, which was helpful for improving plant resistance, root activity, and grain-filling at late growth stages.minirhizotron;