Understanding the seasonal dynamics of photosynthetic capacity of plants and its relationship with leaf traits is of great significance for accurate simulation of ecosystem carbon cycle. In this study, we measured in situ photosynthetic light and CO₂ response curves of Artemisia ordosica over an entire growing season in the Mu Us Desert, and analyzed the relationship of leaf nitrogen content (N_mass), specific leaf area (SLA) with the photosynthetic parameters of A. ordosica. As a result, the maximum net photosynthetic rate (P_nmax), apparent quantum yield (α), maximum carboxylation rate (V_cmax), maximum electron transportation rate (J_max) were relatively higher in the late spring and early autumn in the growing season, largely fluctuated in summer. P_nmax, α, V_cmax and J_max ranged as 13.79-33.31 μmol CO₂·m^-2·s^-1, 0.020-0.053 mol·mol^-1, 27.25-89.10 μmol·m^-2·s^-1 and 24.19-62.18 μmol CO₂·m^-2·s^-1, and averaged at 23.77 μmol CO₂·m^-2·s^-1, 0.037 mol·mol^-1, 56.29 μmol·m^-2·s^-1 and 42.44 μmol CO₂·m^-2·s^-1 respectively. The light compensation point (LCP) and CO₂ compensation point (C_o) did not change significantly over the growing season. Correlation analysis showed that photosynthetic parameters P_nmax, V_cmax and J_max were positively correlated with N_mass and SLA. The results further confirmed that the N_mass and SLA were important factors affecting the photosynthetic capacity of A. ordosica. The relationship between photosynthetic parameters and leaf traits obtained in this study can be used to help build parametric models of ecosystem processes.