A pot experiment was conducted to analyze the effects of Funneliformis mosseae on endogenous hormones and photosynthesis in leaves of Sorghum haipense grown in soil contaminated with Cs. The results showed that Cs stress profoundly promoted abscisic acid (ABA) synthesis and decreased indoleacetic acid (IAA), gibberellin (GA), and zeatin riboside (ZR) contents in Sorghum haipense leaves, which led to significant increases in ABA/IAA and ABA/GA ratio. However, F. mosseae inoculation reduced the IAA, GA and ZR decreasing amplitudes and the ABA increasing range, which would maintain the ratio of ABA/IAA, ABA/GA and ABA/(IAA+GA+ ZR). Radionuclide cesium pollution significantly reduced the photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr), which caused the plant photosynthetic efficiency to be lower than control. F. mosseae could alleviate the negative effect caused by cesium pollution on plant photosynthetic efficiency. It is suggested that to improve the efficiency of photosynthesis and anabolin, enhance plant tolerance and improve bioremediation efficiency, arbuscular mycorrhizal fungi (AMF) such as F. mosseae could be introduced into the field of phytoremediation in radionuclide contaminated soils.