In this paper, mainly research the surface soil heavy metal pollution in cities. First of all ,we find out the spatial distribution of eight kinds of main metal elements in the urban; we adopt the improved gray model to establish evaluation system about urban pollution heavy metal element degree, and then to evaluate the pollution degree of heavy metal element in the city area. Eight heavy metals have been in dimension reduction by means of correlation analysis and principal component analysis, comprehensive variables can be got. By calculating the rotating component matrix, we got objective reason of metal contamination. We analyzed transmission characteristics of heavy metal pollutants and build model to determine the location of the pollution sources. We introduced the field theory the basic assumption , calculated various factors which lead to the change of one point of concentration. The differential equation model can be got which reacted geological environment evolution mode through the mass conservation. Finally we determine the location of the pollution sources and the evolution of the urban geological environment mode.