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In Huanshandak Sandland China, net photosynthetic rate (P-N), transpiration rate (E), stomatal conductance (g(s)), intercellular CO2 concentration (C,), water use efficiency (WUE), photochemical efficiency of photosystem 2 (F-v/F-m), and leaf nitrogen content were compared for Hedysarum ftuticosum var. mongolicum (H.f m.), a nitrogen fixing shrub, and Salix gordejevii (S.g.), a nitrogen non-fixing shrub. PN, E, and g, of the two shrubs were similar in trends, i.e. two peaks were observed in diurnal Courses. However, except C-i, other parameters of H.f m. were higher during the measured days than those of S.g. The midday depression of P-N was mainly due to decrease in stomata conductance and to reduction of F-v/F-m at midday. The higher P-N of H.f m. was consistent with the higher leaf N content and there was a positive relation between them. In addition, several C-4 traits were found in H.f.m., i.e. high saturation irradiance and WUE, low dark respiration rate, and C,, which partly resulted in higher P-N. This seems to indicate that the C-3 plant H.f.m. may have C-4 photosynthesis pathway or C-4 enzymes.