Tunnel　foundation-pit　through　Meilan　Airfield　in　Hainan,　which　is　open　cut,　adopts　the　mixed-support　structure　of　anchor　rope　and　steel　support.　The　project　of　preserving　the　foundation　pit　and　monitoring　distortion　is　given.　The　process　of　construction　is　monitored.　The　dynamic　change　of　the　internal　force　and　distortion　is　controlled.　The　features　of　shifting　and　force　change　in　the　support　structure　are　studied　during　construction.　The　results　show　that　(1)　the　axial　force　of　anchor　rope　changes　a　lot　at　the　beginning　of　construction,　but　gets　gentle　later;　(2)　after　building　the　steel　support,　the　axial　force　has　a　tendency　of　growing　uninterruptedly　and　the　result　has　little　change　and　gets　gentle　finally;　(3)　the　horizontal　displacement　of　pile　body　gets　small　with　the　increase　of　the　depth　of　foundation　pit　and　is　the　largest　at　the　top　and　zero　at　the　bottom.