Our pot experiment of heavy metals of Pb, Ni and Cd and soil investigation of nine cities in Guangdong Province indicated the thresholds of total Pb and Ni of the Environmental Quality Standard (GB15618-1995) unreasonable for the acid soils (gradeⅡ, pH<6.5), they should be decreased to 100 mg/kg from original 250 mg/kg for Pb and increased from 40 mg/kg to original 60 mg/kg for Ni. If according to the new thresholds, 5.25% and 7.21% of soils in Guangdong could be judged to be contaminated by Pb and Ni respectively which are consistent to the percentages of Pb and Ni in crops exceeding the Maximum Levels of Contaminants in Foods, which are 3.90% for Pb and no for Ni respectively.