The soybean cyst nematode ( Ichinohe, SCN) poses a significant threat to soybean yield, often leading to total crop failure in heavily infested areas. Identifying key resistance genes is essential for enhancing soybean resistance to SCN. This study demonstrates that pre-treatment with a bacterial extract, CPT, can enhance SCN resistance in soybean roots by increasing lignin content and peroxidase (POD) activity. Further investigation revealed that the Class III POD gene (Glyma.02G171600) is upregulated under SCN stress, correlating with increased peroxidase activity and lignin content. Overexpression of significantly bolstered SCN resistance, as evidenced by reduced SCN numbers, slowed SCN development, heightened lignin deposition, and elevated POD activity. Conversely, silencing had the opposite effect. These findings suggest that positively regulates SCN stress by enhancing lignin content and POD activity, thereby inhibiting SCN invasion and development. This study identifies as a candidate gene for soybean breeding programs aimed at improving SCN resistance and provides a theoretical foundation for the development of related bio-based seed coatings and SCN-resistant breeding efforts.