Analysis and evaluation of concentrations of heavy metals in farmland soil polluted by pollution water leakage during high-risk arsenical chemicals destruction in Nanjing were carried out by the statistical analysis of survey data and distribution of concentrations of heavy metals were also studied. Then four kinds of heavy metals in the contaminated area were identified out of seven kinds. Different evaluation standards were adopted to evaluate the heavy metal pollution by using the method of pollution index. The results showed that the main pollutants in the research area were As, Cr, Cu and Hg, among which As and Cr were associated with the event and could also be affected by the surrounding residents’ living activities. While the pollution sources of Cu and Hg had nothing to do with the event. The complex pollution index of heavy metals accumulative pollution was 3.57 if taking the upper limit of regional control point (St-1) as evaluation standard, which indicated that the soil was severely contaminated by Cu and Hg. While evaluated with the secondary standard (St-2) of Environmental quality standards for soils (GB/T 15612-1995) and the limited values of Farmland environmental quality evaluation standards for edible agricultural products (HJ 332-2006) as assessment standard, the complex pollution index of heavy metals were 1.58 and 1.60, which meant that it was not suitable for planting pollution-free vegetables or other corps for eating in the area. But if assessed with guidelines for health risk to heavy metals in vegetable plantation soils (St-3), those edible plants such as leafy and melons in the contaminated area maybe posed in hazard due to their different absorbency of heavy metals.