From　the　commuters＇　acceptable　perspective,　using　the　utility　function　of　constant　elasticity　of　substitution　(CES),　the　paper　formulates　a　fixed　demand　commuting　model　based　on　the　combination　policy　of　tradable　credit　scheme　and　encouraged　carpooling,　in　which　a　coefficient　for　government　support　on　carpooling　behaviors　is　added　into　the　constraint　condition　of　travel　budget,　and　then　makes　an　analysis　on　commuters＇　mode　choices.　The　results　show　that　this　combination　policy　can　effectively　guide　some　solo　commuters　become　the　carpool　commuters,　and　the　commuting　individuals　can　reduce　their　travel　budget　without　damaging　their　original　commuting　demand,　although　the　budget　reduction　for　individuals　preferring　solo　commuting　is　relatively　small.　Additionally,　it　shows　that　there　exists　a　feasible　region　for　setting　the　adjustment　factors　and　encouraged　carpooling　coefficients,　and　there　is　a　corresponding　lower　bound　of　adjustment　factor　for　different　encouraged　carpooling　coefficient.　Once　the　adjustment　factor　and　the　encouraged　carpooling　coefficient　are　given,　the　credit　price　is　uniquely　determined　by　the　market,　and　it　is　higher　for　a　lower　adjustment　factor　and　a　higher　encouraged　carpooling　coefficient.　©　2017,　Editorial　Board　of　Journal　of　Systems　Engineering　Society　of　China.　All　right　reserved.