The risk control values of soil are crucial to remediation of contaminated sites. Based on that the calculation of risk control value often ignore the differences between surface and deep soil, the tiered health risk assessment approach is performed to evaluate the risk control values of soil. The heavy metals in soil and site characteristic parameters of a mechanical processing factory in Chongqing are investigated, the tiered health risk assessment approach was displayed for this contaminated site. The results showed that the health risk of Cd and Hg in some soil samples were unacceptable. The risk control values of Cd, Hg and Zn were 7.23 mg.kg-1, 4.61 mg.kg-1 and 4070 mg.kg-1 for 0 m to 4.3m under the ground, respectively while they were 20.96 mg.kg-1, 9.89 mg.kg-1 and 21500 mg.kg-1 for 4.3m to 8m under the ground, respectively. Compared with the single risk control values, the risk control values of tiered health risk assessment approach can effectively reduce the amount of polluted soil for remediation.