Background　Being　subjected　to　bullying　is　a　significant　risk　factor　for　non-suicidal　self-injury　(NSSI)　among　adolescents.　Parental　support,　peer　support,　and　social　connectedness　play　protective　roles　in　mitigating　NSSI　in　this　population.　However,　the　precise　impact　of　the　combined　effects　of　parental　and　peer　support　on　bullying　and　NSSI　requires　further　investigation.　Methods　This　study　employed　the　Child　and　Adolescent　Social　Support　Scale,　Delaware　Bullying　Victimisation　Scale,　Social　Connectedness　Scale,　and　the　Ottawa　Self-Injury　Inventory　to　survey　1277　Chinese　adolescents.　Polynomial　regression　analysis　and　response　surface　analysis　were　applied　to　examine　the　mediating　role　of　bullying　and　social　connectedness　in　the　relationship　between　parental　and　peer　support　matching　and　NSSI.　Results　The　results　indicate　that　parental　support　(r　=　0.287,　P　＜　0.001),　peer　support　(r　=　0.288,　P　＜　0.001),　and　social　connectedness　(r　=　0.401,　P　＜　0.001)　were　protective　factors　against　NSSI　in　adolescents.　Conversely,　bullying　(r　=　0.425,　P　＜　0.001)　acts　as　a　risk　factor　for　NSSI　in　this　population.　Adolescents　with　low　parental　and　peer　support　experienced　more　bullying　than　those　with　high　parental　and　peer　support,　while　those　with　low　parental　but　high　peer　support　experienced　less　bullying　than　those　with　high　parental　but　low　peer　support　(R＜^＞2　=　0.1371,　P　＜　0.001).　Social　connectedness　moderated　the　effect　between　bullying　and　NSSI　in　this　model　(beta　=　0.006,　P　＜　0.001).　Limitations　Due　to　the　under-representation　of　participants　and　lack　of　longitudinal　data　support,　the　explanatory　power　of　causality　between　variables　was　limited.　Future　studies　should　include　national　samples　and　incorporate　longitudinal　studies　to　enhance　the　generalisability　and　robustness　of　the　findings.　Conclusion　This　study　reveals　the　influence　mechanism　of　parental　and　peer　support　matching　experienced　by　adolescents　on　bullying　and　NSSI　and　the　moderating　role　of　social　connectedness.　These　findings　enrich　the　developmental　theory　of　adolescent　NSSI　and　provide　reference　for　the　prevention　and　intervention　of　adolescent　NSSI　behaviour.