A　field　monitoring　programme　was　carried　out　for　the　cut　and　cover　railway　tunnel　near　Meilan　Airfield　in　Hainan　province,　and　varied　laws　on　deflections　and　internal　forces　of　excavation　retaining　and　protecting　were　obtained.　There　are　several　monitoring　on　clusions　as　follows:　1)　The　horizontal　displacements　of　retaining　structure　increases　with　the　construction　duration　and　tends　to　be　stable　gradually　after　the　foundation　pit　excavation　is　completed.　The　largest　displacement　appears　on　about　one　third　depth　of　the　excavation.　2)　The　axial　force　of　cables　changes　greatly　during　the　excacation　of　the　foundation　pit,　and　sand　and　water　effuse　quickly　between　high-pressure　rotating　piles,　which　has　great　influence　on　the　axial　force　of　cables.　3)　The　steel　supports　adoptes　strict　control　standards　and　has　some　potential　bearing　capacity.　The　axial　force　of　steel　support　changes　steadily　and　fluctuates　very　little.