Abstract:The fine root growth patterns of Caragana korshinskii in a 5-year old plantation in the Loess Plateau region of Northwest Shanxi were investigated by using minirhizotron technique. By defining root length density (RLD, mm?cm-3) as basic fine root parameter, and net root length density (RLDnet, mm?cm-3) and net root growth rate (RLDNGR , mm?cm-3?d-1) as derived parameters, the RLDNGR of C. korshinskii seedlings and its relationships with the environmental factors (air temperature, precipitation, soil temperature and soil water content) in the growth season of 2007 were analyzed. The results showed that the averaged RLDnetwas (2.923±1.767)mm?cm-3；and the averaged RLDNGR was (0.113±0.069) mm?cm-3?d-1. The 50-100cm soil layers were the primary growth zone of the fine roots, where the averaged RLDNGR was 15 times that of 0-50cm soil layers. There existed a distinctive seasonal change pattern of RLDNGR from April to September, and it increased rapidly from early April to early August and reached a peak in the middle of August, and then decreased gradually, and became negative in late September. The seasonal growth pattern of fine roots in C. korshinskii seedlings was significantly and positively related to air temperature. The cumulative RLDnetwas 14.613mm?cm-3 in the annual growing season, and the cumulative net productivity was 1.4613×108m hm-2 in the same period.