Abstract: In order to explore the value of carbon storage of returning farmland to forest tree species, the biomass and its allocation of Kernel-apricot plantations at different forest ages were studied .The sample trees (tree layer) and sample plots (herb and litter layer)harvest method were adopted to get the biomass at different ages (6a, 12a, 18a)of Kernel-apricot plantations in Xiaowutai region of zhangjiankou The results showed that: (1) The stand biomass was 15.81t.hm_-2、31.43t.hm_-2、50.53t.hm_-2at 6a, 12a and 18a, respectively; (2)Most biomass(83.72%~96.11%) of Kernel-apricot plantation were concentrated in the tree layer, and increased with ages; the next was the herb layer made up 1.46% to 10.82% ; litter biomass contributed smallest,just made up 2.43% to5.46%; (3) The organic biomass allocation was difference between young and middle as well as old plantations, and differ from other tree spices. The organic biomass allocation were stem>branch>root>leaf>fruit at 6a, and branch>root>stem>fruit>leaf at 12a and 18a, respectively.