This paper studies the effects of grassland improvement on distributions and circulations of nutrients in terrestrial ecosystems, taking Jian'ou Niukenglong Grassland Ecosystem Experimental Station as a case. During two years experiment, the land cover types had been transformed from desert slope-land to grasslands. The experimental results indicate that with the increase in vegetation coverage, the soil total concentrations of nitrogen, phosphorus, and potassium grow rapidly, but that of aluminum decreases obviously. The increases in the total concentrations of nitrogen, phosphorus, and potassium are mainly the consequences of changes of the factors affecting soil evolution, e.g., soil moisture, and changes of soil evolution processes, e.g., weathering rate and decrease of soil erosion. The changes are caused by land coverage growth during the processes of land cover change from desert slope-land to grassland. Conversely, with the change of the land cover types, the increase of land coverage, the activity of aluminum accelerated as well, the down-penetration and lateral penetration of aluminum have been strengthened. Therefore, the loss of aluminum within the experimental terrestrial ecosystem was inevitable, and the total concentration and content of aluminum in the soil have become smaller and smaller, though the growth of grass has been absorbing some amounts of aluminum. Land cover change also affects the circulations of nutrients in terrestrial ecosystem, for the purpose of study on nutrient circulations, we choose plant's absorption, litter and reservation of nutrients to establish the index to indicate the situations of nutrient circulations within terrestrial ecosystems. The results made it clear that in the two land cover types, i.e., two grassland ecosystems, the sequence of nutrient circulation indices are N＞K＞P＞Al in Chamaecrista rotundifolia (pers) green ＋ Pasalum thunbergii and P＞N＞K＞Al in Glycine max var. ＋ Pasalum thunbergii. On the basis of the study, we can conclude that land cover change affects both distributions and circulations in terrestrial ecosystems, different changes have distinct influences on distributions and circulations, and different nutrients are affected to varying degrees in some contents.