Abstract: The experiment was conducted in Inner Mongolia Grassland Ecosystem Research Station. The results show that the stocking rate was 4.0 sheep·hm2 within 1hm2 pasture fenced for 113 days ( warm seasons), and that the amount of S at the top of 0～30cm soil and in plants were 95.6 % and 4 % in the whole grazing system, respectively. The soil was a great amount of S pool. The 93.7 % of total S was accumulated in roots in the plants. The rate of S biological cycling was about 0.40 in the grazing sheep system. The amount of S through feces and urinary return was as 6 times as through litter decomposition. Therefore grazing sheep speeded up S return, but no influence on S biological cycling rate was observed because the intaken S by 4 sheep was only 0.4 % of the whole grazing system.