Aims <p>Maize (<i>Zea Mays</i> L.) is one of the major food crops in the world, and salt stress has become one of the main environmental constraints on maize yield. Poly-γ-glutamic acid (γ-PGA), as an environment-friendly green molecular material, plays an important role in plant growth and regulation. In this project, the effect of γ-PGA on salt tolerance of maize and its mechanism were studied.</p> Methods <p>In this study, the effect of γ-PGA in maize under the salt stress was observed using the solution culturing and soil pot method. And the mechanism of γ-PGA in the salt resistance were analyzed.</p> Results <p>The application of γ-PGA could significantly improve the salt resistance of maize by increasing the ratio of K⁺/Na⁺, the content of proline, enhancing the activities of antioxidant enzymes in maize, and could also induce the expression of genes associated with osmotic stress, Na⁺/H⁺ antiporters, potassium high-affinity transporters, high-affinity K⁺ transporters, and antioxidant enzymes, which collectively enhanced the osmotic, ionic, and oxidative stresses resistance in maize. Additionally, an analysis of rhizosphere soil bacterial community diversity and structure revealed that γ-PGA enriched salt-tolerant plant growth-promoting bacteria (PGPBs) such as <i>Salinimicrobium</i>, <i>Pseudomonas, Denitromonas</i>, <i>and Halomonas</i> under saline conditions.</p> Conclusions <p>γ-PGA enhanced salt resistance of maize by increasing the osmotic, ion, and oxidative stresses resistance and enriching the salt-tolerant PGPBs in rhizosphere soil. This study emphasized the possibility of γ-PGA to improve crop salt resistance and soil ecological environment under soil salt condition and promote the utilization of saline land.</p>