[Objective] The life history strategies of dominant species in patches and their responses to nutrient restriction, stoichiometry characterization of dominant species were studied in response to seasonal variation, which was expected to provid a scientific basis for the study of plant population succession and change process.[Methods] 3 typical patches, patch A(Stipa breviflora), patch B(Stipa breviflora+Astragalus melilotoides), patch C(Artemisia scoparia+Sophora alopecuroides+Cynanchum komarovii) were recognized and in which the dominated species were sampled, and its total carbon, total nitrogen, and total phosphorus contents were measured. Ratios of C:N, C:P, N:P were calculated and analysis of their variances were conducted. Stepwise linear regression analysis of stoichiometry of the patches was performed.[Results] The results showed that the changes of carbon(C), nitrogen(N), phosphorus(P) and their stoichiometry characterization of the dominant species in three patches were different during the growing season, and the seasonal variation characteristics were also different among the three patchesseason. The contents of C among the dominant species, and among the patches as well, had no significant differences. N content of S. breviflora was lower than than the values of other dominant species, which resulted to the significantly smaller level of the N content in patch A. P content of patch A increased along the growing season, while of patch C, it experienced an initial decrease and a succeeding increased. For patch A plants, there was no significant seasonal variation in C:N values, the values of C:P and N:P were significantly higher in spring than those in summer and in autumn. C:N, C:P and N:P values of the dominant species in patches B and C had significant differences. However, the seasonal variation was different:for patch B all values decreased except of C:N value, C:N, C:P and N:P values of patch C all increased first and then decreased.[Conclusion] The C, N, and P contents of three patches showed different correlations, patch A showed a defensive strategy, patch B showed a competitive strategy, while patch C showed a coexistence of competitive and defensive strategies.