Abstract:The paper deals with the translocation,accumulation and attenuation of azodrin inside plane tree following stem brush and their mathematical expression.It is shown that azodrin is used to research on control of pests in plane tree.The following conclusions are drawn:(a)azodrin is transfered in the conductive tissue near the cambium up and down after stem brush;(b)azodrin content in the application site decreases exponentially,and that in the canopy reaches the maximum about two weekes after its application,and then decreases down to zero;(c)more azodrin is contained in the tender branches and leaves than that in the old ones;(d)azodrin has a long life to control pests after stem brush; (e)stem brush of azodrin or its aqueous solution can kill about 95%of slug caterpillar and inhibit the generation of borers in plane tree,and reduce the foliage losses by 60-80%. The conclusion will provide tEe basis for the further study.