The seasonal dynamics of nutrient and energy of fine roots in C. equisetifolia plantations of different ages was studied at Chihu forestry farm of Hui′an county, Fujian province from January to November in 2005. We obtained the following results: (1) There was significant seasonal dynamics of six elements in the fine roots of different aged C. equisetifolia plantations. N concentration of dead fine roots was higher than that of living fine roots, and was relatively higher in summer and winter. P concentration of fine roots fluctuated with a decreasing trend except for the living fine roots of 12 year-old plantation. K concentration was higher in winter than in the other seasons. The highest Ca concentration in March and July was found in living fine roots of 5 year-old plantation and dead fine roots of 18 year-old plantation, while Ca concentration remained little change for other aged plantations. Mg concentration decreased from January to September and then increased in November. C content fluctuated with time. (2) The similar trend was found for N, P and Mg; and for K and Ca, respectively; C concentration fluctuated with plantation age. (3) The ash content, gross caloric values and ash free caloric values changed with “V” type, and were relatively high in March and July or September, respectively. (4) The ash content, gross caloric values and ash free caloric values tended to increase with the increasing plantation age. It was concluded that the nutrient and energy dynamics of fine roots varied with seasons and plantation ages. To discuss matter cycling and energy flow of forest ecosystems, we should pay attention to these characteristics of different stands.