Abstract: The combined effects of Cu, Cd, Pb and Zn on the growth and activity of the seminal roots of wheat (Triticum aestivum) were studied by the method of quadratic regression revolution design. The mathematical models describing the above relations were established. As for the toxicity to the root vitality, their single effects, marginal utility and combined effects between two heavy metals were analyzed. The results showed that Pb had the most important effect on the activity of root,and then,Cu,Cd and Zn in sequence. The interaction between Cu and Cd, Cu and Zn, Zn and Cd, Cd and Pb had great effects on the activity of seminal roots. Furthermore, among the concentration range of 0 to 20 mg稬^-1, as for Cu and Zn, the lowest density had the biggest marginal utility, while Cd and Pb had the biggest ones at the highest density.