With the development of urbanization, ozone (O₃) pollution is becoming more and more concerned in the world including China in recent years. Ornamental grass species play an important role in urban greening and landscape design for urban ecological construction. However, little information is known about the response characteristics of ornamental grass species to O₃ pollution. An experiment was conducted to study the changes of the physiological characteristics in leaves of two common landscape ornamental grass species:Pennisetum alopecuroides ‘White’ and Calamagrostis epigeios exposed to the different concentrations of elevated O₃ (EO):80 nmol/mol (EO-80), 120 nmol/mol (EO-120) and 160 nmol/mol (EO-160) in open top chambers (OTCs). The results showed that:(1) during the short term (7 d), with the increase of O₃ concentrations, the contents of chlorophyll and carotenoids in leaves of P. alopecuroides ‘White’ showed a decreasing trend compared with the control group, and there was no significant change for C. epigeios. (2) Net photosynthetic rate (P_n) and stomatal conductance (g_s) of the two ornamental grass species leaves decreased significantly under EO-120 and EO-160 for 7 d, compared to the control. In addition, the decreasing degrees of these photosynthetic parameters in leaves of P. alopecuroides ‘White’ were larger than those of C. epigeios. (3) Under elevated O₃ concentrations, malondialdehyde (MDA) content in leaves of the two ornamental grass species showed an increasing trend compared with that under the control. When treated with EO-160 for 21 d, MDA content increased by 30.2% in the leaves of P. alopecuroides ‘White’ (P<0.05), and 13.5% in leaves of C. epigeios (P > 0.05), which indicated that P. alopecuroides ‘White’ suffered from a higher injury of membrane lipid peroxidation than C. epigeios under EO-160. (4) When treated with EO-120 and EO-160 for 21 d, soluble protein content in leaves of P. alopecuroides ‘White’ decreased significantly by 24.2% and 43.1% compared with the control, respectively; and decreased significantly in leaves of C. epigeios by 19.03% and 22.9%, respectively (P<0.05). (5) Peroxidase (POD) activity in leaves of the two ornamental grass species decreased with the increase of O₃ concentrations, and the activity of superoxide dismutase (SOD) first increased and then decreased. (6) Based on the comparison of physiological characteristics and the analysis of principal components, we found that that C. epigeios was more tolerant to O₃ than P. alopecuroides ‘White’, and the former could show higher value of application than the latter, especially in O₃-polluted urban areas.