The　amount　of　wear　serves　as　a　crucial　indicator　for　evaluating　the　rolling　contact　fatigue　performance　of　various　materials.　To　enable　online　and　continuous　wear　measurement　of　specimens　during　testing　and　to　efficiently　assess　the　wear　performance　of　plastic　gear　materials　under　varying　working　conditions,　an　online　measurement　method　for　rolling　contact　wear　loss　was　hereby　proposed　based　on　line　structured　light.　Initially,　the　point　cloud　of　the　specimen　surface　was　captured　using　a　line-structured　optical　sensor　mounted　on　the　rolling　contact　fatigue　tester.　Subsequently,　regarding　the　unique　characteristics　of　plastic　specimens,　a　comprehensive　wear　calculation　method　was　developed.　The　experimental　results　demonstrated　a　measurement　precision　of　+/-　0.1　g　and　an　average　relative　error　of　6.31　%.　This　system　accurately　measures　wear　loss　in　specimens　and　enables　observation　of　surface　morphology　changes,　thus　serving　as　a　valuable　in-situ　measurement　tool　for　assessing　the　rolling　contact　fatigue　performance　of　plastic　gear　materials.