The agricultural land suitability assessment based on natural characteristics of land blocks is traditionally the basis of agricultural and/or land use planning. However the assessment is static and can not incorporate potential land use changes. A dynamic approach emerging recently, i.e., matter element based analysis, has provided an effective way for land use planning. Taking the suitability grade of land use, assessment indicators and their characteristic values as matter elements, this paper established a matter element analysis model for land use suitability assessment, using of sutra field, controlled field, weight value and relating degree from field survey and expert system. This model was then applied in Yuejiagou small watershed of Langzhong Municipality in Sichuan Province, the results show that the proportion among agriculture, forestry and animal husbandry is tending to appropriateness; the economic and ecological indices of the lands has been increased from 1529.80 and 1460.94 to 1719.99 and 1758.21 respectively after regulation. The regulation also results in changes in the landscape patterns. The indices of diversity and evenness of landscape patterns have increased from 1.3028 and 0.6108 to 2.0920 and 0.8463 respectively, or by 60.58% and 38.56% respectively. However, the indices of dominance and contagion have decreased from 0.6431 and 0.7467 to 0.2106 and 0.7125 respectively. It is indicated that the land use in the small watershed tends to be reasonable; the spatial distribution of patches trends to be uniformed; patch congregation is gradually dispersed. This example has proven that the matter element analysis approach can not only overcome the man-made influences and improve the precision, but also can implement the exact regulation to the specific patches in the structure regulation of land use in small watershed.