We measured total N and P concentrations of leaf, fine root, and soil (0-15, 15-30, 30-45 cm) in 5-, 10-, 15-, 20-, and 25-year-old Cunninghamia lanceolata plantations in Huitong, Hunan Province. The objective of this study was to determine the variation in the N and P stoichiometry of leaf-root-soil during the whole life process of Cunninghamia lanceolata plantations, and provide basic data to guide the management of Cunninghamia lanceolata plantations. The following results were obtained. (1) Stand age had a significant influence on soil N and P concentrations and the N:P ratio (P < 0.01). Soil layer only had significant influence on soil N concentrations (P < 0.01). Soil N concentrations decreased with increasing soil depth, whereas soil P concentrations and the N:P ratio showed no significant difference with increasing soil depth. In each soil layer, N and P concentrations initially decreased and then increased significantly with increasing stand age (P < 0.05). Soil N and P concentrations were the highest in 25-year and 5-year Cunninghamia lanceolata plantations, respectively, and were the lowest in 10-year and 15-year Cunninghamia lanceolata plantations. The soil N:P ratio increased with increasing stand age, although not significantly. (2) Stand age and organ type had a significant influence on plant N and P concentrations and the N:P ratio (P < 0.01). Leaf and fine root N and P concentrations showed a significant "V-shaped" pattern with increasing stand age (P < 0.05), whereas fine root P decreased slightly in 20-year Cunninghamia lanceolata plantations. Leaf and fine root N and P concentrations were the lowest in 15-year Cunninghamia lanceolata plantations, and were the highest in 5-year and 25-year Cunninghamia lanceolata plantations, respectively. The leaf N:P ratio did not change significantly with increasing stand age. The range of leaf N:P ratios was 11.79 to 14.86. For all stand ages, leaf N:P ratios were lower than 14, except for 20-year Cunninghamia lanceolata plantations, indicating that N was the main factor limiting the growth of Cunninghamia lanceolata. The fine root N:P ratio increased significantly with increasing stand age (P < 0.05), and the range of fine root N:P ratios was 9.00 to 22.89. (3) During the whole life process of Cunninghamia lanceolata plantations, N and P concentrations were significantly different between leaf, fine root, and soil in the order leaf > fine root > soil (P < 0.05). There were significant correlations between leaf and fine root N and P stoichiometry (P < 0.05), except for the leaf and fine root N of 25-year Cunninghamia lanceolata plantations. However, no significant correlations between 0-15 cm soil and leaf and fine root N concentrations were found. There were significant correlations between 15-30 and 30-45 cm soil and leaf and fine root N and P concentrations in 5-year and 10-year Cunninghamia lanceolata plantations (P < 0.05), whereas there were no significant correlations between soil and leaf and fine root N and P concentrations in 15-, 20-, and 25-year-old Cunninghamia lanceolata plantations. During the whole life process of Cunninghamia lanceolata plantations, there were significant correlations between leaf and fine root and soil P concentrations and the N:P ratio. It was concluded that with forest development, there have been changes in the nutrients of leaf, fine root, and soil, which reflect the strong links between leaf, fine root, and soil N and P stoichiometry.