Abstract: A pot-culture experiment was conducted to investigate the effect of inoculation of two arbuscular mycorrhizal fungi (Glomus intraradices and Glomus claroidum) on δ13C value and gas exchange parameters of Leymus chinensis, one of the dominant grass species in Inner Mongolia grassland. The parameters were measured at 45, 60 and 75 days after sowing. Results showed that colonization of the two fungi increased phosphorus concentration, stomatal conductance and photosynthetic rate of Leymus chinensis. However, intrinsic water use efficiency and δ13C values of the plants were not significantly affected.