In order to understand the characteristics of carbon, nitrogen, phosphorus, and the stoichiometry characteristics of Pinus sylvestris var. Mongolica plantation ecosystem in Horqin Sandy land, we used the space-temporal exchanging method and selected four forests with different stand ages (15, 25, 35, and 45 years) but with similar site condition as the objects. The contents of carbon, nitrogen, phosphorus, and the stoichiometry characteristics in the needle leaf, litter, and soil were analyzed, then their changing characteristics as stand age increasing and the relationships between them were explored. The results showed that:(1) The contents of C, N, and P were in order of needle leaf > litter > soil, C/N, C/P, and N/P were in order of litter > needle leaf > soil, whose differences were significant among needle leaf, litter, and soil. (2) There were significant differences for C, N, P concentrations, and C/N, C/P stoichiometry ratios among forests with different stand ages. The C, N, and P contents of leaf, litter, and soil were the highest in the 35-years-old forest. (3) Compared to other regions, the leaf and litter performed the same characteristic with higher C and P, lower N, higher C/N, higher C/P and lower N/P. (4) The N/P ratios of all forests with different ages were lower than 14, but there was no significant difference between them, which indicated that the P. sylvestris plantation was restricted by N, but the N limitation was not significant between forest ages. (5) There were significant correlations between the contents of C, N, P and C/N, N/P ratios of the leaf, litter and soil, which indicated that the C, N, P elements of P. sylvestris plantation were transferred between 3 libraries of the conifer, litter, and soil, but its internal maintenance mechanism needs further study.