Abstract: In order to know the particle-size distribution of Mo Us Desert,top soil(0-5 cm) from grassland,woodland,cultivated land,fixed dune,semi-fixed dune and moving dune of Mo Us Desert were collected.We calculated particle-size parameters using Moment law computation to study topsoil particle-size distribution of the Mo Us Desert.The results showed: the topsoil particle-size of different sandy land types was mainly in sandy range(1 000-50 μm),and the content percentage was 41.22%-97.63%.Silt(50-2 μm) was 0-51.61%.Clay(<2 μm particles) was 2.71%-10.38%.The average particle-size of semi-fixed dune and fixed dune was 145.491 μm and 157.563 μm respectively,which was a lower level among the land types.The average particle-size of fixed dune and cultivated land was 128.782 μm and 118.175 μm,which was a medium level among the types.The average particle-size of grassland and woodland was 94.667 μm and 108.819 μm,grain-size of which was fine.The particle-size distribution of moving dune was coarsest.The particle-size classification of moving dune and semi-fixed dune was better,which showed a strong positive bias and a sharp peak.The average particle-size distribution of cultivated land,woodland and grassland also displayed a positive bias,but theirs drift rate was lower,the peak was also gentler.The particle-size distribution was significantly different among the land types of Mo Us Desert,which led to the difference of wind erosion.From the view of spatial variation,the average particle-size of topsoil changed the coarse particles to the fine particles gradually from northeast to southwest in Mo Us Desert.