Background <p>Spinal cord injury (SCI) is a severe nervous trauma and the underlying mechanism of miR-1287-5p in its pathogenesis remains incompletely elucidated.</p> Objective <p>This research seeks to elucidate the molecular mechanism of miR-1287-5p in regulating inflammatory responses following SCI.</p> Methods <p>The expression levels of miR-1287-5p and MAP3K9 were measured using qRT-PCR. Pearson correlation tests scrutinised their associations with clinical indices. ROC curve analysis was conducted to evaluate it diagnostic value for SCI. CCK-8 and ELISA assays were employed to evaluate cell viability and protein expression levels, respectively. The direct interaction between miR-1287-5p and MAP3K9 was confirmed through dual-luciferase reporter assays.</p> Results <p>miR-1287-5p was markedly down-regulated in SCI patients and correlated with pain scores, LEMS, and ASIA grade.ROC curve analysis indicated that miR-1287-5p has potential as a diagnostic biomarker for SCI. Overexpression of miR-1287-5p enhances cell viability, reduces the production of inflammatory cytokines, and specifically binds to MAP3K9, thereby inhibiting its expression.</p> Conclusion <p>miR-1287-5p serves as a potential diagnostic biomarker for SCI and modulates the inflammatory response in SCI through direct targeting of MAP3K9.</p>