Soil salinization seriously reduces crop growth. Arbuscular mycorrhizal (AM) fungi infect crop roots by forming mycorrhizal symbiosis which can promote crop growth by increasing soil nutrient and water acquisition and multi-stress tolerance. In this study, we collected rootzone soils of three widely distributed salt-tolerant plants (Phragmites australis, Tamarix chinensis, and Suaeda salsa) in the Yellow River Delta National Nature Reserve. The community composition of soil AM fungi was analyzed by high-throughput sequencing technology. The single spores of different AM fungi were isolated and identified by wet-sieving decanting-sucrose centrifugation, host propagation and 18S rRNA sequencing. The effects of different AM fungi on the growth and photosynthetic capacity of maize seedlings in saline soil were examined in pot experiment. The results showed that: (1) The AM fungal community composed of 32 species belonging to 10 families and 12 genera, dominated by Glomus, Claroideoglomus, and unclassified Glomeromytoca. The AM community composition was closely related to soil conductivity and TOC. (2) We isolated six AM fungal strains with strong infection and stable colonization in maize roots. Strain AM3 had closer phylogenetic relationships with the family Glomeraceae and Claroideoglomus, and AM1, AM5, AM6, AM8, and AM9 were closely related to the genus Paraglomus or Glomus. (3) All of the six AM fungi can alleviate the salt stress and promote maize seedling growth. Particularly, AM3 and AM5 strains significantly improved plant height, biomass, and leaf photosynthesis. Our results revealed the differences in AM fungal community compositions in rootzone soils of salt-tolerant plants in the Yellow River Delta and evaluated their salt tolerance and growth promotion in maize seedlings, providing a scientific reference for selecting and applying AM fungi to improve crop growth in saline-alkali agricultural fields in the Yellow River Delta.