Firstly，a contour map of the 8 kinds of heavy metal concentration of urban area of a city is drawn using the MATLAB software to get the spatial distribution of different kinds of heavy metal element in the city，and the preliminary conclusion of the pollution degree in 5 districts. What’s more，Nemero comprehensive pollution index method is used to qualify the pollution degree of various areas，and to achieve the pollution grade of all kinds of heavy metal in each area at the same time. The main cause of the heavy metal pollution in the surface soil of the city is analyzed by using the table of the comprehensive evaluation of pollution.