Abstract: The basic method of Principle Component Analysis (PCA) methodology and its application in evaluation of soil corrosivity are introduced. On the basis of this methodology, the authors build up a mathematical model about comprehensive factors evaluation of soil corrosivity, and obtain the index weight for soil resistivity, water cut, natural potential, pH value and soil composition, which can be used to determine the classification of soil corrosivity. The field tests in Chongqing and Hejiang display that the result of soil corrosivity obtained from the Principle Component Analysis (PCA) methodology is quite fitted with that of site coupon. It is concluded that the Principle Component Analysis (PCA) methodology is feasible and effective in soil corrosivity assessment.