Abstract: The response of different plant groups to simulated rainfall changes in summer, increased snow in winter and spring, and nitrogen fertilization application in late June were studied in an alpine Kobresia humilis meadow in Qingzang plateau. The results indicated that the response of summed dominated ratio (SDR) and above-ground biomass in different plant groups were not significantly different with 20%-40% rainfall reduction or 20%-40% increased rainfall in 1999. A 100% increase in snow in winter and spring was more favorable to the growth of plant groups than were other rainfall treatments. Both a single late June application of 150 N kg·hm-2 and 300 N kg·hm-2 in soil increased the coverage ratio, height ratio and SDR of grasses. The coverage ratio, height ratio and SDR were significantly decreased at the strong N application (300 N kg·hm-2). There were obvious compensatory effects between grasses and forbs at the application of 150 N kg·hm-2. The sensitivity of the three plant groups was quite different. Grasses were most, forbs were less and sedges were least sensitive to simulated rainfall and available N in the improved disturbing condition. Forbs were most, grasses were less, and sedges were least sensitive to simulated rainfall and available N in the undesirable disturbing condition. It seemed that sedges were most tolerant to fluctuation in environmental resources. Simulated rainfall increasing by 20%-40% could moderate the effect of lower precipitation in a water deficient year (1999), while rainfall decreased 20%-40% could intensify the effect of drought.