Abstract: The karst canyon is a typical karst ecological fragile area, in which the land cover changes’ research is of great significance to the ecological protection of mountainous areas and the optimization of land resources. Taking the karst canyon of Guizhou as the research area, the land cover data from 2000 to 2020 were selected to explore the changes in land cover and the law of topographic differentiation by extracting three topographic factors of altitude, slope, and aspect. The results showed that: (1) The land cover area of the study area was varied significantly from 2000 to 2020. The areas of woodland, grassland, water area, and construction land were increased, while the area of arable land was decreased; (2) As the altitude increased during the study period, the area of arable land from 2000 to 2020 presented an upward-decreasing-increasing-declining trend; The area of woodland generally showed an upward trend first and then downward, with a peak value of altitude approximately at 1800 ~ 2200 m; There were two relatively high-value areas in grassland and construction land, appearing at the altitudes of 1200 ~ 1400 m and 2200 ~ 2400 m, 1200 ~ 1400 m and 1800 ~ 2000 m, respectively; The water area was mainly distributed at the altitudes of lower than 800 m and 2000 ~ 2200 m; (3) As the slope rose, the areas of arable land, woodland and grassland would increase first and then decrease, showing the highest slope value observed at 10° ~ 15°, 15° ~ 20°, and 10° ~ 15°, respectively; The area of construction land showed a downward trend with an increase of slope; (4) With the change of slope, the areas of the flat lands were less distributed in the Non-slope area, the woodland, the grassland and the construction land; Meanwhile, the construction land in 2020 was relatively high in the southwest slope.