Abstract: To investigate the influence of ore exploration on soil environment, the authors conducted investigations in the rice field topsoils of the Le'an River. The concentrations of heavy metals Cd, Cu, Pb and Zn in the topsoils were analyzed, and the soil environmental quality on the basis of the environmental background value criteria were evaluated by single factor index and Nemerow multi- factor index method, respectively. The results show that the soils were polluted by heavy metals Pb, Cd, Cu and Zn, with the National Standard (GB15618-1995) as the evaluation standard. In addition, heavy metals pollution in various degrees occurs in the areas along the lower and middle reaches of the Lea'n River. The results indicate that the average concentrations of heavy metals (Cd and Cu) in the soil exceed the background values, and the integrated contamination index of all samples has exceeded 7.82. The heavy metal levels in the soils are closely related to local geological environment and controlled by one or more leading factors of geological environment．