Abstract: The 9-, 17-, 30- and 37-year-old Robinia pseudoacacia plantations in the loess hilly region were investigated to study the dynamics and allocation patterns of carbon and nitrogen storage. The results showed that the ranges of carbon and nitrogen contents were 435.9-493.4 g·kg^-1 and 6.8-21.0 g·kg^-1 in the arbor layer, 396.3-459.2 g·kg^-1 and 14.2-23.5 g·kg^-1 in the herb and litter layer, and 2.7-10.7 g·kg^-1 and 0.2-0.7 g·kg^-1 in the soil layer, respectively. The branch was the major carbon and nitrogen pool in the arbor layer, accounting for 46.9%-63.3% and 39.3%-57.8%, respectively. The maximum storage values were 30.1 and 1.8 Mg·hm^-2 for carbon and nitrogen, respectively, in the 0-20 cm soil layer in the 37-year-old R. pseudoacacia plantation. The total carbon and nitrogen storage in the R. pseudoacacia plantation ecosystem increased with increasing forest age, and the maximum values were 127.9 Mg·hm^-2 and 6512.8 kg·hm^-2 for carbon and nitrogen storage, respectively, in the 37-year-old R. pseudoacacia plantation. Soil layer was the major carbon and nitrogen pool of R. pseudoacacia plantation ecosystem, accounting for 63.3%-83.3% and 80.3%-91.4%, respectively.