Using samplings from different aged Larix principis-rupprechtii Mayr.plantations located in Taibai Mountain,Shaanxi and Xiaolong Mountain,Gansu of China,respectively,we analyzed total nitrogen(N),total phosphorus(P) in soil,root,stem and leaf tissues,plant biomass,root characteristics and their correlations.The results showed that:(1)N concentrations in soil decreased with increases in soil depth in different aged Larix plantations,but P concentrations in soil did not display such a pattern.Significantly positive linear correlations were found between N and P concentrations in 0—60 cm soil.(2)N and P concentrations in leaves were the highest among all plant tissues.N and P concentrations in leaves and fine roots were significantly higher than those in coarse roots and stems.Significantly positive linear correlations were detected between N and P concentrations in all plant tissues.(3)Biomass and accumulated N and P amount in different plant tissues increased with increases in ages of plantations.Biomass of stem and accumulated N and P amount in leaves were higher than those of other tissues.(4)There were positive linear correlations between specific root lengths,and N concentrations in 0—20 cm soils,N and P concentrations in fine roots.(5)Total length of coarse roots,mean length of proximal roots,maximum radial distance and maximum root depth increased with increases in ages of plantations.Negative linear correlations were found between concentrations of N and P in coarse roots and lengths of coarse roots,and maximum radial distances of coarse roots.Those results indicated that,specific root lengths increased with an appropriate increase about N concentrations in 0—20 cm soils,when N and P concentrations in coarse roots down,the roots will extend outward to increase the range of absorption of N and P nutrients in order to meet the normal growth of the Larix plantations.