Abstract: Plant root characteristics and their persistence and performance are closely related, but there are few studies of this relationship between different varieties of alfalfa. This research evaluated the relationship of root characters with biomass and persistence of 10 alfalfa varieties. The tested varieties were planted in 2001 and have been grown for 10 years. The main measurements were done in 2011 and some related data were used from measurements from 2001. There were significant differences in root traits between the alfalfa cultivars (P＜0.05). Xinjiang Daye and Gongnong No.1 had stronger taproots and crowns and more lateral roots. The taproot and crown of Super 7, Jindera and Eureka were smaller and there were fewer lateral roots. The root characteristics of L33,Amierica Daye,SD-006,Gannong No.1 and Ranbule were moderate. In addition, significant correlations were found between root morphological index and persistence and biomass. The varieties which had stronger taproots and especially strong crowns, and more lateral roots had better persistence. Varieties which had stronger taproots and crowns had higher biomass. These results indicate that Xinjiang Daye and Gongnong No.1, which had strong roots and crowns with better biomass and longer persistence, are more suitable varieties to be widely planted in the Hexi corridor.