The present study provides an analysis on landscape pattern changes of sand dunes at different scales in Horqin Sandy Land. The resulted showed that the areas, patch numbers, landscape area percent and largest patch index of mobile dune at larger scale (892.74 km2) increased gradually from 1975 to 1995, but the areas of mobile dune and semi-mobile dune decreased after 1995. The areas and patch numbers of mobile dune at medium (110.42 km2) and small scales (14.14 km2 or 14.10 km2) increased from 1975 to 1985, but they decreased after 1985. The analysis of the index and value of desertification process indicated that the desertified lands at larger scale are in the development process of desertification from 1975 to 1995 and are in the reversion process after 1995, and the desertified lands at medium and small scales, are in the development process of desertification from 1975 to 1985 and are in the reversion process after 1985. The study scales had an important effect on the changes of spatial landscape pattern in the sandy land. The changes of landscape pattern of Horqin Sandy Land are determined mainly by the changes of numbers and areas of mobile dunes resulted from the unsuitable human activities.