Sixteen tree-rings of Polar (P. Euramericana) were collected in the different function districts of Kaifeng City, China. Concentrations of Cu and Zn in the xylem of tree-rings from 1990 to 2009 were measured using F-AAS, and that of Co using ICP-MS. The results show that concentrations of Cu and Zn in tree-rings in the control area do not vary significantly in the period from 1990 to 2009 and much lower than that in urban areas. The accumulation sequences of Zn in tree-rings in different urban districts appear increasing trends in the period, and that of Cu present waved rising trends. The sequences of Co in tree-rings both in urban and control area had no significant change in the period. Copper and Zinc are the typical anthropogenic metals, and Co is a natural source metal. We can understand the heavy metal pollution changes in urban area from their accumulation sequences in tree-rings.