【Objective】Long-term unreasonable farming methods have aggravated the degree of soil salinization, seriously restricting the sustainable development of agriculture and posing a threat to regional food security. Arbuscular mycorrhizal (AM) fungi can form a symbiotic relationship with most higher plants and help plants to improve their tolerance to saline-alkali stress. However, in alkaline soil environment, the interaction regulation mechanism between AM fungi, host plants and soil microorganisms is not clear, and the differences caused by different inoculation methods are also lack of systematic comparison. The purpose of this study was to explore the effects of different AM fungal inoculation methods on the growth and physiology of Pennisetum alopecuroides under alkali stress.【Method】In this study, the dominant species Pennisetum alopecuroides in Songnen Plain was selected as the experimental object. Five inoculation treatments were designed: NS (inoculated with high temperature and high pressure sterilized in situ soil microbial agent); NL (inoculated in-situ sterilized soil with 38 μm filter-filtered soil leachate microbial agent); NB (inoculation of sterilized in-situ soil microbial agent treated with benomyl); AS (inoculation of unsterilized in-situ soil solid microbial agent); AL (unsterilized in situ soil liquid bacteria were inoculated). All treatments were cultured under normal control (CK) and alkali stress (SS) conditions for 60 days. Then the growth status, mycorrhizal infection rate, physiological resistance index and soil glomalin content of the plants were systematically determined.【Result】According to the analysis of the actual measurement results, the infection effect and root development performance of AS treatment were the best, indicating that the microbial community in the soil could cooperate with AM fungi to improve root development and enhance the alkali resistance of plants. NS treatment caused a significant decrease in plant stress resistance due to the complete inactivation of all microorganisms, confirming the indispensability of soil microorganisms in the alkali resistance mechanism. Although NL treatment alleviated the negative effects caused by sterilization to a certain extent, the overall improvement was limited due to the loss of some active microbial components during the filtration process. NB treatment could effectively inhibit the activity of AM fungi while retaining the function of other non-target microorganisms, which is an effective method to distinguish and test the specificity of AM fungi. Although the infection rate of AL treatment was low, it still showed a growth-promoting effect, which may be related to the fact that the microbial metabolites in the bacterial agent can independently participate in plant stress resistance and growth regulation.【Conclusion】The results showed that different inoculation methods of AM fungi had significant effects on the growth and physiological status of Pennisetum alopecuroides under alkali stress, and AS treatment enhanced the plant’s stress resistance through reciprocal symbiosis. NB treatment is the preferred method to inhibit AM fungi, and has the least interference to soil microecology. It is suggested that AS treatment should be preferred in actual inoculation. This study can provide reference and data support for vegetation restoration and efficient utilization of AM fungal resources in saline-alkali land.