Non-suicidal　self-injury　(NSSI)　is　a　significant　public　health　concern,　with　severely　impacts　for　adolescent　mental　health.　As　awareness　of　the　harmful　effects　of　NSSI　grows,　there　is　an　increasing　emphasis　on　understanding　the　underlying　mechanisms　in　this　age　group.　This　study　explores　how　internalizing　and　externalizing　issues　related　to　parent–child　conflict　influence　NSSI,　focusing　on　the　roles　of　negative　self-perception　(self-criticism)　and　association　with　deviant　peer　affiliation　in　this　relationship.We　used　questionnaires　to　assess　variables　including　parent-child　conflict,　self-criticism,　Deviant　peer　affiliation,　internalizing　and　externalizing　issues,　and　instances　of　NSSI.　A　conditional　process　model　was　employed　to　examine　the　interrelated　pathways　through　which　these　factors　influence　each　other.　A　total　of　804　adolescents　successfully　completed　the　questionnaires.　Our　analysis　revealed　that　the　severity　of　NSSI　was　positively　associated　with　the　level　of　parent-child　conflict　(b　=　0.22,　p　＜　0.001).　Self-criticism　and　internalization　issues,　as　well　as　deviant　peer　affiliation　and　externalizing　issues,　acted　as　dual　mediators　in　this　relationship,　explaining　17.72%　and　7.93%,　of　the　variance,　respectively.　Among　the　examined　analyzed,　the　influence　of　parent–child　conflict　on　NSSI　through　deviant　peer　affiliation　was　not　statistically　significant.　This　study　highlights　the　significant　relationships　between　parent–child　conflict　and　NSSI　in　adolescents.　This　relationship　is　mediated　by　a　dual-chain　involving　self-criticism　and　internalization　issues,　as　well　as　deviant　peer　affiliation　and　externalizing　issues,　all　of　which　are　identified　as　risk　factors　for　NSSI.　Understanding　these　dynamics　can　inform　the　development　of　targeted　interventions　to　reduce　NSSI　among　adolescents.　©　2025　Wiley　Periodicals　LLC.