By using the methods of field investigation, soil sampling and laboratory analysis, the carbon content, storage in eucalyptus (Eucalyptus sp.) plantation ecosystems near Liuzhou, Guangxi Province was studied. The results showed that the carbon content (percent of dry weight) of the understory layer in all plantations at 2a, 3a, 4a were 41.9%, 41.1%, 40.85% respectively, there was no significant difference (P<0.05). The litter content ranged, from highest to lowest as follows: 2a >4a >3a. The carbon content of soil from 0-60 cm depth ranged from 0.32%-0.65%. The total carbon storage of eucalyptus plantations at 2a, 3a, 4a were 47.2, 85.76, 101.9 t/hm2, respectively. The carbon stored in the tree layer increased with ages, there was significant difference between them. Carbon storage in tree layer at 3a, 4a accounted for 38.61% (33.12 t/hm2), 57.42% (58.51 t/hm2) of the entire stored carbon within each of the respective ecosystems, they contributed much to entire ecosystems. The carbon stored in the understory layer of eucalyptus plantations at 2a, 3a, 4a accounted for 0.86%, 2.69%, 1.49% of the total carbon stored in the ecosystem respectively，the carbon stored in the litter of eucalyptus plantations at 2a, 3a, 4a accounted for 8.55%, 3.98%, 2.62% of the total carbon stored in the ecosystem respectively. The Eucalyptus plantations soil carbon storage were 37.54, 46.92, 39.2 t/hm2 respectively, there was significant difference between them, the soil carbon with 0-20 cm depth accounted for 41.2% of total soil carbon stock, and the soil carbon with 20-40 cm depth accounted for 31.88%. The carbon stored in the tree layer and soil combined accounted for the majority of the carbon stored within these plantation systems, where as the carbon stored in the understory and litter contributed the least to the total carbon stock. The study offered the basic data for short -rotation Eucalyptus plantation in Guangxi area.