The influences of root diameters, branch orders, seasons of birth, soil depths and stand ages on fine root lifespans were studied using minirhizotrons in the 18- and 90-year-old Chinese fir (Cunninghamia lanceolata) plantations in Nanping, Fujian Province. The median lifespans (ML) of fine roots increased with the diameter, with the corresponding ML of (125±47) d, (158±16) d, (248±18) d, and (272±53) d for roots of ≤0.3 mm, 0.3 0.6 mm, 0.6-1.0 mm, and >1.0 mm in the younger stand, and of (95±20) and (200±17) d for roots of ≤0.3 mm and 0.3 0.6 mm in the old-growth stand. Roots of 0.6-1.0 mm and >1.0 mm in the old-growth stand had the accumulative survival rates over 50% at the end of the experiment. The accumulative survival rates of high order roots were significantly higher than those of the first order roots in both stands, with ML of (180±13) d and (200±18) d respectively for the first order roots and with the accumulative survival rates over than 50% for the high order roots when the experiment was over. In the younger stand, roots born in the autumn had significantly higher accumulative survival rates than those born in the summer, while those born in the winter and autumn had significantly higher accumulative survival rates than those born in the spring and summer in the old-growth stand. The ML was (216±16) d, (248±12) d, (172±6) d, and 125 d respectively for roots born in the winter, autumn, spring and summer in the younger stand, and was 383 d, (127±23) d, and (106±19) d respectively for those born in the autumn, spring and summer in the old-growth stand. Roots born in the winter in the old-growth stand had an accumulative survival rate over 50% at the end of the experiment. The accumulative survival rates increased significantly with soil depths for roots of the old-growth stand, with ML of (156±14) d and (241±24) d respectively for the 0-20 cm and 20-40 cm depths and an accumulative survival rate over 50% for the 40-60 cm depth at the end of the experiment. There was no significant difference in the accumulative survival rates for roots of the younger stand among soil depths, with ML of (187±19)d, (216±28) d, and (120±47) d, respectively. There was no significant difference in the survival curves between the stands for roots with the same diameter class, root order, season of birth or soil depth, except those born in the summer and those inhabited the 40-60 cm depth for which significant differences between stands were found.