Research purposes: This paper researched earthwork quantities automatic statistics for railway roadbed cross section based on spatial analysis. In the traditional railway design，the cross-sectional statistical earthwork rely entirely on artificial measure，which is inefficient，difficult to ensure accuracy，and cannot meet the design requirements， therefore，it is necessary to carry out a cross-sectional earthwork intelligent statistical research. Firstly，in order to accurately extract the classification of each section of the soil，the paper realized parameter identification for every object. After graphical preprocessing, the spatial analysis tracking method was adopted to search the smallest closed encirclement by counterclockwise for every section of soil classification，at the same time to search the greatest closed encirclement by counterclockwise for the whole earthwork quantities，calculating the areas for all closed encirclement with calculus. In the end，the earthwork quantities were output automatically，and formed a unified and standardized excel.