A　series　of　model　tests　are　conducted　to　investigate　the　installation　and　extraction　behavior　of　the　modified　suction　casson(MSC)　embedded　in　marine　clay　by　taking　the　MSC　dimensions,　shear　strength　of　clay　and　installation　method　into　account.　It　is　found　that　the　discrepancies　between　the　final　penetration　depths　of　the　MSC　with　the　aspect　ratio　of　1.0　and　2.0　and　the　corresponding　regular　suction　caissons　(RSCs)　are　2%　and　6%,　indicating　that　the　MSC　can　penetrates　into　the　clay　to　a　desired　depth.　During　suction-assisted　installation,　the　internal　compartment　and　the　external　skirt　are　found　to　disturb　the　soils　around　the　caisson,　leading　to　the　decrease　of　the　penetration　resistance　compared　with　the　penetration　resistance　during　jacking　installation.　Based　on　the　limit　equilibrium　method,　the　expressions　for　estimating　the　required　suction　to　penetrate　the　MSC　into　clay　and　the　penetration　resistance　were　proposed.　In　addition,　the　variations　of　the　water　pressure　in　the　suction　caisson　and　uplift　resistance　during　suction　caisson　extraction　are　also　obtained.　The　results　show　that　the　water　pressure　in　suction　caisson　firstly　increases　sharply　to　the　maximum　value　with　the　extraction　displacement,　and　then　decreases　to　a　certain　value.　It　is　also　found　that　the　MSCs　and　RSCs　can　not　be　fully　extracted　by　injecting　water　into　the　caisson.　The　expression　obtaining　the　extraction　resistance　of　the　MSC　is　proposed　to　guide　the　foundation　design.　©　2020,　Editorial　Office　of　Chinese　Journal　of　Geotechnical　Engineering.　All　right　reserved.