Based　on　the　general　situation　and　geology　condition　of　the　Xiamen　Xiang＇an　sub-sea　tunnel,　the　construction　effects　on　different　methods　of　excavation　and　pre-supporting　were　simulated　by　FLAC.　The　rational　method　of　excavation　and　pre-supporting　was　proposed　through　analysis　and　comparison　of　the　computed　results.　The　construction　technology　of　double-side　pilot　heading　excavation　method　and　full-section　curtain　grouting　was　introduced.　The　simulated　results　of　the　double-side　pilot　heading　excavation　method　show　that　the　deflections　of　arch　crown,　side　walls,　and　bottom　plate　will　be　reduced　obviously;　the　tunnel　section　will　be　forced　in　much　more　rational　distribution;　and　there　will　not　be　large　areas　of　stress　concentration.　The　suggestions　include:　1)　to　select　the　double-side　pilot　heading　excavation　method,　2)　to　adopt　full-face　curtain　grouting　for　advanced　consolidation,　3)　and　to　apply　grouting　by　small　diameter　steel　tubes　and　other　supplementary　reinforced　measures　during　the　excavation.