With　the　increase　of　vehicle　ownership　and　the　rapid　growth　of　urban　traffic,　the　problem　of　congestion　in　the　off-ramp　area　of　the　main　expressway　has　become　the　main　factor　restricting　overall　section　efficiency　and　inducing　traffic　accidents.　This　paper　focuses　on　the　problem　of　group　collaborative　lane-changing　behaviors　of　off-ramp　vehicles　and　through　vehicles　in　off-ramp　areas　and　proposes　four　kinds　of　vehicle　group　collaborative　strategies　based　on　different　road　space　balance　conditions.　According　to　a　three-lane　expressway　scene,　a　VISSIM-based　simulation　model　is　built　and　the　optimization　scheme　is　simulated　and　evaluated.　The　simulation　results　show　that　with　the　increase　of　traffic　flow　in　off-ramp　areas,　a　flow-balance　strategy　for　downstream　lanes　where　off-ramp　vehicles　merge　with　the　outside　lane　in　advance　is　more　advantageous.　When　vehicles　are　leaving　the　main　road,　if　traffic　flow　is　heavy,　the　flow-balance　strategy　for　lanes　where　off-ramp　vehicles　merge　with　the　outside　lane　in　advance　(for　example,　the　proportion　of　off-ramp　vehicles　in　three　lanes　is　0　:　0　:　1)　is　better;　otherwise,　when　the　traffic　flow　on　the　main　road　is　relatively　small,　the　flow-balance　strategy　for　lanes　where　off-ramp　vehicles　are　distributed　in　lanes　with　different　ratios　(e.g.,　1　:　3　:　6)　is　better.　What　is　more,　for　future　traffic　management　in　connected　vehicle　environments,　it　can　be　concluded　that　collaborative　vehicle　lane-changing　strategies　with　different　traffic　flow　states　can　help　to　enhance　traffic　efficiency.