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Based on the collection of land use maps of three representative years (1972, 1986 and 1995) with a scale of 1∶100 000, which were derived from interpreted aerial photographs and field surveys, landscape pattern were studied in Wenchuan County of Aba Prefecture, northwest of Sichuan Province, China. Six land use categories were classified according to the actuality of the study area and digitized by manual with the assistance of Geographic Information System (GIS). Landscape spatial and temporal changes were analyzed quantificationally by a series of structure, shape, pattern indices, which indicated that grassland dominates in number of patch while both grassland and shrub-land dominate in total area of patch over time. During the last 23 years, the fractal dimension of grassland and shrub-land were decreased while the other types were increased. Highest dominance and fragmentation and lowest diversity characterized the landscape of 1972. In 1986, the landscape pattern had the highest diversity and lowest dominance and fragmentation, which is contrary to the pattern in 1972. Slight change of diversity, dominance and fragmentation has been displayed from 1986 to 1995.