Drought and high concentration of calcium are the main characters of the karst soils, and always show great heterogeneity in the karst ecosystems. In order to explore the effects of AMF on the photosynthetic and growth characters of maize (Zea mays L.) under various stresses, three treatments including drought, high concentration of calcium (high Ca), and their combination (double stress) were applied to potted maize seedlings. The results showed that the colonization rate of the AMF to maize seedlings was following the sequence of: control > drought > double stress > high Ca. Compared to the control group, the biomass, net photosynthetic rate (Pn) of the seedlings were decreased in the three treatments. Under non-inoculation conditions, the biomass of maize seedlings subjected to drought, high calcium and double stress were 3.2%, 63.7%, 76% lower than that of control respectively, while those of Pn were 33.4%, 86.9%, and 98.8%. In the same time, under inoculation conditions, compared with the control, the seedling's biomass in drought, high calcium and double stress were 16.3%, 78.4%, 80.2% lower, and net photosynthetic rate were 9.7%, 92.8%, and 91.7% lower. Additionally, compared to the seedlings without AMF, those vaccinated AMF showed significantly higher biomass, chlorophyll content, transpiration rate (Tr), maximum photochemical efficiency, and absorbed more phosphorus, when subjected to the drought and double stress. On the contrary, in the environment of high calcium, the AMF only enhanced the content of chlorophyll, maximum photochemical efficiency, while there was no increase in terms of plant biomass, Tr and the absorbing amount of nitrogen and phosphorus. Moreover, the interaction of AMF×drought and AMF×double stress had significant effects on the Pn of seedlings, while no significant effects of AMF×high Ca were found on the Pn. AM fungi can assist the plant to absorb more phosphorus, enhancing the contents of chlorophyll, improving the activity of light reaction center, increasing the plant stomatal conductance, so as to enhance photosynthesis ability to promote the growth of plant. This research can provide references for a reasonable utilization of AMF and increasing agricultural productivity in the karst ecosystem.