Arbuscular mycorrhizal fungi (AMF), which engage in a mutualistic symbiosis with the roots of most plant species, have been well studied for their ability to alleviate heavy metal stress, including that of copper (Cu), in plants. Most mycorrhizal studies have focused on AMF effects on host plant nutrient uptake. However, few studies have investigated plant physiological responses during plant-microbe interactions, which are necessary to understand the efficiency of the phytoremediation of heavy metal pollution. Elsholtzia splendens, a widely distributed Cu-tolerant plant, is usually found in the Cu mining areas of southern China and is colonized by symbiotic AMF. This study examines the effects of AMF on the physiological responses of E. splendens leaves under Cu stress. A controlled pot experiment was performed to investigate the effects of AMF inoculations and Cu additions on E. splendens leaves' photosynthetic pigment contents, anti-oxidation enzymatic activities, antioxidant contents and lipid peroxidation. The plants, which were grown on a mixture of sterilized soil and sand, were inoculated with AMF (non-inoculated plants were controls), with or without the addition of Cu (1000 mg/kg and 0 mg/kg, respectively). The results showed that AMF could well colonize the roots of E. splendens under both Cu treatments. The plant root biomass, stem biomass, leaf biomass, inflorescence biomass and total biomass of E. splendens under Cu stress were lower than in the control. Inoculations with AMF significantly increased the plant root biomass, stem biomass, leaf biomass, inflorescence biomass and total biomass of E. splendens under Cu stress by 36.1%, 138.9%, 47.3%, 68.4% and 79.7%, respectively, and significantly decreased the root shoot ratio by 26.3%, indicating an alleviating effect of Cu inhibition on E. splendens growth. Compared with the control, the chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, Chl a+b content [Chl (a+b)], carotenoid content and chlorophyll a/b ratio (Chl a/b) under Cu stress significantly decreased by 56.2%, 52.6%, 55.1%, 49.8% and 7.5%, respectively. Additionally, the superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), glutathione (GSH) and ascorbic acid (AsA) contents in the leaves of E. splendens under Cu stress significantly decreased by 44.8%, 45.0%, 61.0%, 43.7%, 49.2% and 31.1%, respectively, while the membrane relative permeability (MRP) and malondialdehyde (MDA) contents significantly increased by 61.5% and 106.4%, respectively. With the Cu addition, the AMF inoculation significantly increased the Chl a, Chl b and Chl (a+b) contents in E. splendens leaves by 36.7%, 30.6% and 34.8%, respectively, and the GSH and AsA contents by 55.1% and 29.6%, respectively. It also enhanced the SOD and APX activities by 33.7% and 66.1%, respectively, while it reduced the MRP and MDA contents by 18.0% and 20.2%, respectively. In conclusion, AMF inoculations could effectively alleviate the damage of Cu stress on E. splendens by increasing the photosynthetic pigment contents and the antioxidant capacities, while decreasing the lipid peroxidation of cell membranes and the relative conductivity, which might be important for Cu stress adaptation and the improved productivity of E. splendens.