Through spatial overlapping analysis, this paper discussed the effects of the two topographic features derived from Digital Elevation Model (DEM) on spatial heterogeneity of soil organic matter (SOM) in a low mountainous region. The results showed that: ①SOM spatial variability was basically consistent with the change of slope’s gradient in Mengding Mountain, and SOM content was highest at the gradient range from 15o to 35o; ②the effect of slope’s aspect on SOM spatial heterogeneity was not as intensive as slope’s gradient, but it was obvious at the gradient range from 110o to 180o; ③the effects of slope and aspect on SOM spatial distribution were nearly independent, but in some special areas, for instance, in gullies, the interactive influence of the two attributes on SOM heterogeneity was also obvious.