Abstract:【Aim】 To provide a theoretical basis for the application of Bacillus subtilis in agricultural production and biosafety, this study used tomato as the experimental crop to explore the preventive effect of Bacillus subtilis 262XY2' on tomato fusarium wilt in potted plants and to evaluate its impact on biochemical indicators of tomato plants and rhizosphere soil health. 【Method】 Experimental groups treated with different amounts of solid bactericides (0.5%, 1.0%, 2.0%, 3.0%, and 4.0% of seedling substrate quality) and a control check (CK) with no added solid bactericides were established for tomato seedling cultivation and four tomato plant leaves were transplanted into each pot. Six weeks after planting, the preventive effect of the tested bacteriological agent on tomato fusarium wilt was determined using an established disease severity grading method. Biochemical indicators including tomato plant catalase, peroxidase, superoxide dismutase, chitinase, catalase, N-acetyl-β-D-glucosidase, and urease activities as well as total thiol and tomato rhizosphere soil free amino acid contents were quantitated. 【Result】 In the rhizosphere soil of tomato treated with 0.5% bactericide, the free amino acid content and N-acetyl-β-D-glucosidase and catalase activities were 44.325%, 108.848%, and 16.472% higher than those in CK, respectively. The most potent tomato fusarium wilt preventive effect was 73.485% and was achieved with 1.0% bacterial agent application. Catalase activity in tomato plants treated with 1% bacterial agent and peroxidase, superoxide dismutase, and chitinase activities were 55.742%, 47.404%, 39.433%, and 209.989% higher than those in CK, respectively. Rhizosphere soil urease activity was 12.063% higher than that in CK. All these represent the highest values. Total thiol content was highest with 2.0% bacterial treatment at 191.304% higher than that in CK. 【Conclusion】 In general, 0.5%, 1.0%, and 2.0% inocula increased tomato defense enzyme activities and improved biochemical properties of tomato rhizosphere soil to varying degrees. Higher density inocula (3.0% and 4.0%) exerted no notable effects on these biochemical indices of tomato plants and their rhizosphere soil and even had inhibitory effects.