In this paper, the effects of a PGPR strain, Bacillus subtilis WM13-24 isolated from the rhizosphere of Haloxylon ammodendron, on salt tolerance of perennial ryegrass (Lolium perenne) were investigated. At the same time, Escherichia coli DH5α and B. subtilis GB03 were used as the negative control and the positive control, respectively. The results were as follows: 1) under various salt treatments (0, 150 and 300 mmol/L NaCl), inoculation of WM13-24 increased the biomass, chlorophyll content, root length and root vigour of ryegrass. Especially, under 150 mmol/L NaCl, inoculation of WM13-24 increased the contents of leaf chlorophyll a and chlorophyll b significantly by 44.05% and 53.79%, respectively, and the root length and root vigour significantly by 69.21% and 49.47%, respectively, compared with the blank control (P < 0.05). Under 300 mmol/L NaCl, root length and root vigour were increased significantly by 24.07% and 58.48% by inoculation of WM13-24, respectively (P < 0.05). 2) Under various NaCl treatments, inoculation of WM13-24 increased catalase (CAT) activity and reduced relative membrane permeability (RMP) and malondialdehyde (MDA) content of ryegrass. Especially, under 300 mmol/L NaCl, CAT activity of ryegrass was increased significantly by 64.21%, and relative membrane permeability and MDA content were reduced significantly by 24.56% and 54.24% by inoculation of WM13-24, respectively (P < 0.05). 3) Under various NaCl treatments, inoculation of the PGPR strains increased soluble sugar and proline contents and reduced osmotic potential of ryegrass. Especially, under 300 mmol/L NaCl, the contents of soluble sugar and proline in ryegrass plants inoculated with WM13-24 were significantly increased by 84.41% and 82.71%, respectively (P < 0.05). 4) Inoculation of the PGPR strains increased K⁺ content in both shoots and roots of ryegrass under various NaCl treatments, and decreased Na⁺ content, resulted in increased K⁺/Na⁺ ratio. Especially, under 300 mmol/L NaCl, root K⁺/Na⁺ ratio of ryegrass plants inoculated with WM13-24 was increased significantly by 87.93% (P < 0.05). In summary, this study laid a theoretical and practical basis for the application of PGPR from the rhizosphere of desert plants in improving the salt tolerance of grass and forage plants and cultivating forage crops and turf grasses in saline-alkali areas.