How　the　family　socioeconomic　status　(SES)　is　related　to　internet　altruistic　behavior　(IAB)　among　adolescents,　and　the　mechanism　between　family　SES　and　IAB　is　still　unclear.　We　propose　that　higher　family　SES　is　associated　with　higher　adolescents＇　personal　belief　in　a　just　world　(PBJW)　which,　in　turn,　increases　emotional　intelligence　(EI);　Finally,　EI　is　related　to　IAB.　The　590　adolescents　from　a　public　high　school　in　Northeast　China　were　invited　to　complete　the　family　SES　assessment,　PBJW,　EI　and　IAB　questionnaires.　Results　supported　our　model,　indicating　that　the　effect　of　family　SES　on　IAB　is　mediated　by　PBJW　and　EI　separately　and　sequentially.　An　important　value　of　current　study　is　to　extend　the　relationship　between　family　SES　and　altruistic　behavior　into　the　cyberspace,　and　put　up　a　public　notice　that　the　vital　function　of　PBJW　and　EI.　These　findings　promote　the　expansion　of　the　literature　describing　the　beneficial　factors　that　promote　adolescents＇　participation　in　IAB.