Spatial distribution pattern is important in plant ecology as it affected the dynamics of plant populations, communities and ecosystem processes, which can reveal the dynamic and stability of population and community structure. Stipa krylovii, the zonal vegetation in alpine degraded grassland, has a great significance for understanding ecological processes and sustainable utilization of grassland resources with studies on population patterns of S. krylovii. Study sites locates in the MaChangtan grassland in SuNan country of the north Qilian Mountain (38°47'22.1″-38°52'11″ N,99°45'11.7″-99°57'41.2″ E). with the altitude of 2610-2632 m, the annual temperature of the region is 1-2 ℃, the annual precipitation varies within a range of 270-350 mm, the soil is mainly consisted of mountain chestnut soil, the dominant native vegetation in the region is consisted of perennial grasses and forbs. In July 2010, we recorded fine-scale (0-100 cm) spatial patterns of S. krylovii from 2 m × 2 m grids (2 cm × 2 cm quadrats) in four plots under four kinds of degradation gradients according to community characteristics, population characteristics of S. krylovii, and grassland stocking rate for nearly 10 years: no degradation (＜90%), light degradation (105%-125%), moderate degradation (123%-138%) and heavy degradation (135%-150%). The point pattern analysis and Monte Carlo stochastic simulation method were used to quantitatively analyze S. krylovii population patterns by the software of GetData Graph Digitizer 2.22, VisualFortran 6.5 and Origin 7.5. Based on life history traits, bunch structure, patch characteristics and strategies of ecological adaptation in the community, the mechanisms generating and maintaining these patterns were discussed. The results showed that: First, there were significant effects on patch characteristics of S. krylovii population under the different degradation gradient. The density and population territory area of S. krylovii population in heavy degradation was significantly lower than no degradation, but its total area of hole in heavy degradation was greater than no degradation, and territory density increased firstly and then reduced. Second, the bunch structure of S. krylovii population existed complicated relationships. The small bunch of 0.1-1.0 cm in heavy degradation was greater than no degradation. At the same time, the proportion of big bunch was significantly higher than others in no degradation. Third, there was a difference at different scales. Under no degradation conditions, the spatial patterns of S. krylovii were regular at 0-64 cm scales, but aggregated at 64-100 cm scales; under light degradation conditions they were random at 0-100 cm scales; under moderate degradation conditions, the spatial distributions were random at 0-70 cm scales, but aggregated at 70-100 cm scales; under heavy degradation conditions, there was random as a whole and the scale ranges was from 0 cm to 100 cm. In contrast, the population patch is the basic functional unit of S. krylovii, which can decide the status and role of S. krylovii in the community. Under the role of grazing and interspecies competition, population patches may crumble from center to the edges gradually, and it lead to the spatial patterns changed. Finally, S. krylovii declined in alpine degraded grassland along with population patch broken and mattic epipedon disappeared.