This study developed a method for Soil Organic Matter (SOM) mapping in a lithoidal mountainous area using a stratified strategy under fuzzy inference framework. Environmental variables derived from terrain analysis and remote sensing incorporated with a small number of field samples were used to predict spatial variation of SOM. A new variable, bare soil ratio, representing the fractions of bare soil area inside a pixel of remote sensing images resulted from sub-pixel unmixing technology is used specifically for rocky upland area. A case study in the Hushiha area of North China has shown an improved spatial detail and accuracy of SOM compared to the available traditional soil map of Heibei Province. The proposed method takes full advantages of data with free access such as SRTM DEM and remote sensing images of HJ-A which exhibits massive potential to map SOM efficiently at low cost for a large area.