The aim of this work was to develop a potential ecological risk index to be used as a diagnostic tool for heavy metal contaminated agricultural soils control purposes in mining areas. Taking consideration that the main-road for ecological risk of heavy metal contamination of soil is soil-vegetation-man. The environmental bioavailability largely determines the environmental impact of metal contaminated soils. Using environmental bioavailability explain the environmental toxicity sensitivity of the heavy metals in the soil-vegetation-man ecological system. The model is following: RI=∑^m_i=1E^r_i, with E^r_i= Tⁱ_e×Tⁱ_b×Cⁱ_f. RI= the requested potential ecological risk index for soil; E^r_i = the potential ecological risk factor for the given substance (i); Cⁱ_f= the degree of contamination, Cⁱ_f=Cⁱ/Cⁱ_o , Cⁱ= the metal concentration in the soil, Cⁱ_o= the metal concentration for samples from referring area; Tⁱ_e= the element toxic-response factor for the given substance: Zn=1, Pb=4, Cd=15, Cu=2, Cr=11, Ni=3. Tⁱ_b=（Rⁱ_b / Pⁱ_b）^1/2; Tⁱ_b=the environment bioavailbability ratio factor, Tⁱ_b =（Rⁱ_b / Pⁱ_b）^1/2, Rⁱ_b =[water soluble fraction + exchangeable fraction/total concentration of the metal in soil](100%] for the samples of contaminated soil, Pⁱ_b=[water soluble fraction + exchangeable fraction/total concentration of the metal in soil]×100%] for samples from referring area.