Abstract: Pot experiments were conducted in a greenhouse to study the effects of AM fungi on the growth and photosynthesis under Hg stress, based on the effect of AM fungi on biomass, height, chlorophyll relative content, photosynthetic rate, stomatal conductance, intercellular CO₂, water use efficiency, membrane lipid peroxidation, antioxidant enzyme activities soluble sugar and soluble protein content. The results showed that: (1) Under different Hg pollution conditions, AM fungi could promote the growth of rice plants. (2) The photosynthetic rate and chlorophyll were also increased by AM fungus inoculation, and AM fungi could improve the photosynthesis of rice by promoting the secretion of photosynthetic pigments. (3) AM fungi could decrease the content of MDA and reduce the degree of lipid peroxidation of cell membrane. The activities of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase were also increased by AM fungus inoculation, which indicated that AM fungi could improve the activity of antioxidant enzymes, maintain cell homeostasis, and alleviate the toxicity of Hg. The results of significance analysis showed that when the concentration of Hg was 0.1 mg/kg, the overall growth of rice was better, while a number of physiological indexes were on the high side, indicating that AM fungi could promote the growth of rice and improve the resistance of rice under low mercury concentration. In conclusion, AM fungi can enhance the adaptability of rice to mercury pollution, promote plant growth and development, reduce the toxicity and damage of Hg to rice, and enhance the stress resistance. This effect will be more obvious under the condition of low concentration mercury pollution.