The rate of biological cycles of trace elements in the trees of HaiNan Province are analyzed. The average mass fractions of the trace elements in the trees are as follows: Cu 6 87×10 -6

Zn 21 61×10 -6

Ni 0 68×10 -6

Cd 0 93 ×10 -6

Pb 1 83 ×10 -6

Hg 0 050×10 -6 . Each of them is at normal level. The mass fractions of essential trace elements such as Zn and Cu are higher than those of Pb

Cd

Ni and Hg.The order of the mass fractions in most of the trees is Zn>Cu>Pb>Cd>Ni>Hg.The values of Hg

Cd and Ni in leaves are higher than those in branches

while the value of Cu is usually reverse.The mass fractions of trace elements in trees vary with species of trees and ecological environment.