The research on rules of spatial variation of Soil Organic Matter in plain-hill transitional zones and their affecting factors is of great practical significance to guiding agriculture. This study was oriented to explore variation of soil organic matter (SOM) and its influencing factors in a transitional zone between the Jianghan Plain and the mountainous area in West Hubei) in China. A total of 500 soil samples from the surface soil layer (0～20cm) were collected and analyzed for SOM content. By means of correlation analysis and stepwise regression analysis, out of the 14 affecting factors, seven variables, including elevation, slope, aspect, available iron, soil bulk density, soil gravel degree, clay content that were closely related to SOM, were selected as explanatory variables. OK and GWRK methods were used to interpolate the SOM data into the study area, and ME, MAE, RMSE, r, IP were used as validation indices for determination of prediction accuracy of the models. Results show that GWRK was higher OK and RK in prediction accuracy, which indicates that the local spatial regression model can be used to explain spatial variation of the SOM in the transitional region.The coefficient spatial distribution maps of the GWR model can be used to reflect degree of environmental variables affecting SOM spatial nonstationarity relative to geographical location, which may serve as a basis for exploring dominant affecting factors of SOM relative to terrain condition, and also as an important reference for plotting accurate SOM spatial distribution maps of transitional zones.