The　suction　caisson　for　offshore　engineering　features　fast　installation　and　reuse.　When　offshore　engineering　structure　supported　by　a　suction　caisson　is　decommissioned,　the　suction　caisson　can　be　extracted　by　reverse　pumping　water　for　reuse　and　being　replaced　by　a　larger　one.　Model　tests　were　conducted　to　investigate　effects　of　the　installation　methods,　extraction　methods　and　pumping　rate　on　the　extraction　behavior　of　both　the　regular　suction　caisson　(RSC)　and　modified　suction　caisson　(MSC)　in　sand.　It　was　found　that　when　the　seepage　failure　occurs　in　and　around　the　caisson,　the　extraction　by　reverse　pumping　water　is　terminated.　Under　the　same　pumping　rate,　the　final　extraction　height　and　the　maximum　overpressure　beneath　the　caisson　lid　of　the　MSC　are　greater　than　those　of　the　RSC.　The　final　extraction　heights　of　caissons　installed　by　jacking　are　greater　than　those　installed　by　suction.　Model　tests　on　the　extraction　of　suction　caissons　by　pumping　air　was　also　conducted　and　it　was　found　that　final　extraction　heights　of　the　RSC　and　the　MSC　which　were　extracted　by　reverse　pumping　water　are　greater　than　those　extracted　by　reverse　pumping　air.　Further,　extraction　tests　of　Perspex-made　suction　caisson　were　conducted　to　investigate　the　difference　between　the　extraction　behavior　of　suction　caissons　by　reverse　pumping　water　and　air　into　the　caisson.