The ground-active arthropod diversity response to size of shrub plantations in desertified grassland ecosystems is largely unknown. In the study ground-active arthropods were collected by pitfall trapping beneath shrub canopy of very low, low, medium and high size, with adjacent mobile sandy land as a control. It was found that arthropod dominant taxa from mobile sandy land were significantly distinctive from those from plantations of different shrub size. A considerably lower Sørensen index (i.e., 0.25–0.48) was found between the arthropod communities from mobile sandy land and the canopy of either shrub size, than between those under low and medium/high shrub size (i.e., 0.62 to 0.69). The arthropod total abundance was significantly greater under the shrub canopy of very low size in comparison to that of low and medium shrub size and mobile sandy land, with the intermediate values under shrub canopy of high shrub size. Taxon richness and diversity of arthropod communities were distinctly lower under the shrub canopy of low size in comparison to very low, medium and high shrub size. The shrub size was found to have different effects on the density and richness distribution of arthropod trophic groups (i.e., predators, phytophagous, saprophagous, and omnivorous). It was concluded that shrub plantations could facilitate ground-active arthropod diversity recovery when they were afforested in mobile sandy land. There was a contrasting effect of shrub size on ground-active arthropod diversity recovery versus arthropod abundance when grazing was excluded.