Abstract: To understand how species and stand age affects stoichiometric characteristics of plant leaves, litter andsoil, and the limiting status of N, P nutrients, Pinus armandi and Quercus aliena var. acuteserrata natural forests with 4 stand age groups located in the Qinling Mountains, were selected to test C, N and P stoichiometric characteristics. The results showed that the C, N and P concentrations in each age group of 2 forests were the highest in tree leaves and the lowest in soil. The C concentration in P.armandi leaves was higher than that in Q.aliena var. acuteserrata, while N and P concentrations were lower. Species have extremely significant effects on the stoichiometric characteristics of plant leaves, C content, N content, C : N and C : P of litters and P content and N : P in the soil. Stand age significantly effected on C content of leaves and litters. Also, it has extremely significant affect on P content, C : P, N : P ratio in the soil. The N : P ranges from 7.47 to 12.50, and the N played the dominant role in normal growth of plants.