Big trees had large interfaces with environment, so this dominant position was useful in accumulating heavy metals in highly residensed Nanjing areas. Based on the data of biomass, physical and chemical characters of soil in oak ( Quercus variabilis ) stand, the studies were carried out on the absorption and accumulation of heavy metals at Xiashu long term ecological monitoring station. The results showed that: in different organs of the oak, the contents of heavy metals were quite different, the ranges of them were Pb 0.85～5.60, Cd 0.011～0.167, Cr 0.35～2.25, Ni 0.90～3.90 (μg/g).The heavy metals storage in the oak was 79.75 for Pb, 1.92 for Cd, 21.2 for Cr and 46.80 for Ni (mg/m 2), respectively.The urban forest soil in Nanjing areas was under a very clean condition, owing to forests function of protecting and accumulating airboral depositions. The biological cycles of the elements were described as : annual uptake, Pb 13.79, Cd 0.36, Cr 4.32, Ni 7.83 (mg/m 2) ; annual retention, Pb 9.575, Cd 0.282, Cr 4.32, Ni 5.535 (mg/m 2); annual return Pb 4.21, Cd 0.079, Cr 0.58, Ni 2.29 (mg/m 2) ; turnover period Pb 19, Cd 29, Cr 36,Ni 20 (year).