<p>The industrial application of surfactin has been constrained by the low production capacity of <i>Bacillus subtilis</i>. This study developed a high-yield, high-tolerance surfactin-producing strain through a multi-level metabolic engineering strategy. First, we constructed an enhanced P43 promoter (P43LN) by extending its upstream region from 260 to 520&#xa0;bp and pairing it with a cognate 5′ UTR, which exhibited more than threefold higher activity than the commonly used core P43 promoter, providing a versatile tool for stable and high-level expression of key genes. Based on this, the native <i>srfA</i> promoter in the oilfield-derived <i>B. subtilis</i> TD7 was replaced with the P43 promoter, yielding the engineered strain TP1. Subsequently, systematic knockout of competing antimicrobial peptide synthesis gene clusters (<i>pps</i>, <i>bac</i>, and <i>pks</i>) increased surfactin titer to 2.78&#xa0;g/L. Further synergistic enhancement of NADPH regeneration (via <i>zwf</i> overexpression) and cellular tolerance (via efflux pump gene <i>yerP</i> overexpression) resulted in the final strain TS8, which achieved a shake-flask surfactin titer of 3.51&#xa0;g/L, representing a 102.7% increase in per-OD₆₀₀ productivity. This work successfully integrates promoter engineering, metabolic flux redistribution, and tolerance modules, not only significantly improving surfactin production but also providing a powerful expression and systematic optimization toolkit for <i>B. subtilis</i>, laying a technical foundation for the efficient biomanufacturing of complex natural products.</p> Graphical abstract <p></p>