In order to explore the effect of arbuscular mycorrhizal (AM) fungi on photosynthetic physiology of Lolium perenne under Cd stress，a total of 16 treatments were designed with L.perenne inoculated with or without AM fungi Funneliformis mosseae(FM)，Glomus versiforme(GV)，mixed treatment(FM+GV) and control treatment (NM) in the soil added with Cd content of 0，5，15 and 30 mg·kg-1，respectively.The results showed that Cd treatment reduced the infection of AM fungi.Inoculation with AM fungi significantly increased the plant height，chlorophyll content，fluorescence parameters，N and Cd content in shoots and roots of L.perenne，enhanced photosynthesis and chlorophyll content of plants，and significantly increased the physiological activity of plants.Under the level of 30 mg·kg-1 Cd，the mycorrhizal infection rate of FM+GV treatment was 42.7%，compared with the control，the chlorophyll content，N content in shoot and root in the leaves of L.perenne increased by 26.2%，70.6% and 85.3%；plant height and aboveground dry weight increased by 34.1% and 18.8%；the PS Ⅱ maximum photochemical efficiency and PS II potential activity increased by 4.9% and 19.7%；and the net photosynthetic rate，transpiration rate and gas pore conductivity increased by 19.8%，28.3% and 14.7%；respectively.The activities of superoxide dismutase，peroxidase，soluble proline were 1.3，1.5 and 1.8 times as compared with the control，but the malondialdehyde content decreased by 50.0%.There was a significanty positive correlation between Cd concentration in soil and Cd content in shoot and root，the Cd content in the top and root of L. perenne inoculated with FM+GV reached 88.1 and 606.7 mg·kg-1，respectively.In general，FM+GV treatment had the most significant effect on increasing photosynthetic physiological resistance and Cd absorption and fixation capacity of L.perenne.