Based on the landscape pattern theory, this paper made use of the TM remote sensing images of northern mountain areas of Mianzhu obtained before and after the Wenchuan May 12, 2008 earthquake for the work of land use classification. With the land-use classification map as the data source, the authors studied the disturbance of the earthquake to the landscape pattern in the aspects of classification and landscape level, and discussed the dominance, shape index and degree of fragmentation in different classes on the basis of FRAGSTATS software. The result shows that the woodland was most greatly affected, as evidence by the facts that its dominance was decreased, its degree of fragmentation was raised, and the edge effect was increased by the increasing edge density. In addition, the area of bush-wood and hilly dry field was deduced evidently, and the circulation and CONTAG of the landscape were decreased. In a word, the stability of the ecosystem is worse than that of the pre-earthquake period.