Space　debris　occupies　a　valuable　orbital　resource　and　is　an　inevitable　and　urgent　problem,　especially　for　large　space　debris　because　of　its　high　risk　and　the　possible　crippling　effects　of　a　collision.　Space　debris　has　attracted　much　attention　in　recent　years.　A　tethered　system　used　in　an　active　debris　removal　scenario　is　a　promising　method　to　de-orbit　large　debris　in　a　safe　manner.　In　a　tethered　system,　the　flexibility　of　the　tether　used　in　debris　removal　can　possibly　induce　tangling,　which　is　dangerous　and　should　be　avoided.　In　particular,　attachment　point　bias　due　to　capture　error　can　significantly　affect　the　motion　of　debris　relative　to　the　tether　and　increase　the　tangling　risk.　Hence,　in　this　paper,　the　effect　of　attachment　point　bias　on　the　tethered　system　is　studied　based　on　a　dynamic　model　established　based　on　a　Newtonian　approach.　Next,　a　safety　metric　of　avoiding　a　tangle　when　a　tether　is　tensioned　with　attachment　point　bias　is　designed　to　analyse　the　tangling　risk　of　the　tethered　system.　Finally,　several　numerical　cases　are　established　and　simulated　to　validate　the　effects　of　attachment　point　bias　on　a　space　tethered　system.