A joint model of the temporal and spatial variation of soil properties was built, which integrated traditional statistics, spatial trend analysis, time stability assessment, and geostatistical hybrid model based on GIS. The joint model was used to reveal the spatio-temporal changes of soil organic matter and its influencing factors in Miyun County, Beijing. The results showed that the joint spatio-temporal model could preferably reflect the characteristics of soil organic matter（SOM）for high landscape heterogeneity in detail. SOM displayed medium time stability, and the random parts accounted for the spatial variability increased gradually. Patterns of spatial distribution of SOM content were consistent in different years. The SOM content in high value area gradually decreased over time, and increased in low value area. And the variation was large in high values range and small in low value area. The main factors impacting spatio-temporal variation of SOM were soil texture and land use in the study area. 