In this study, a new resource assessment model was developed based on the theory of arable land classification and Nemerow index method. The model was parameterized using the values of soil fertility and clean indexes which were calculated from the concentrations of major nutrients and heavy metals respectively. The model was tested on the arable lands in six towns in Chongming of Shanghai. The output showed that all lands reached the standard line (≥80), with an average score of 86.01 in the range of 81.90-91.80 The lowest value, from Jianshe Town, was the result of relatively high heavy metal contamination. Based on this theory, a unit of ‘ideal mu’ was introduced into the model as a correction factor to the values of geometric area. This resource assessment model gives decision makers comprehensive information for better management of the arable lands with regard to food security and quality.