Landscape diversity is the result of natural disturbance, human activity and the internal succession of vegetation. It also is a major level of biodiversity. In this paper, the authors established a landscape classification system for Longxi-Hongkou Nature Reserve, Sichuan Province, with vegetation types and land-use being the main classify basis, interpreted two different phases of Landsat TM images before and after the Wenchuan Earthquake of the reserve, developed the landscape spatial pattern of the study area, and analyzed the characteristics of landscape changes before and after the earthquake. The results showed that: 1) After the earthquake, the total number of patches (NP) in the study area increased by 2.36 times, so landscape became more fragmentation; after the earthquake, forest landscape (broad-leaf and coniferous) went into smaller pieces, implying the weakness of its dominant position. Broad-leaf, meadow and rare landscape turned into the new dominant landscape. 2) The SHDI and PAFRAC of the study area increased 11% and 7% respectively. It implied the diversity and heterogeneous of the study area strengthened, and landscape structure was more complex. The Dominance and CONTAG both decreased 30%. It explained that the number of large patches decreased, the landscape contagion of the study area fell and its connection declined. 3) The habitats fragmented, the ability of maintain biodiversity was cut down. Vegetation cover dropped, and edge habitats grew in number, leading to a weaker ability of maintain water, a raising risk of soil erosion, landscape structure destroyed and the protective screen function slipped. Therefore, Wenchuan Earthquake and its secondary disasters as natural disturbance factors have changed the landscape structure and landscape pattern of the study area, undermined the suitable habitats of rare animals and plants, posed a threat to endangered species and natural ecosystems, all those would change the biodiversity and ecology environment of the region.