A　series　of　horizontal　cyclic　loading（resulted　from　wind　and　waves　in　deep　sea）model　tests　on　modified　suction　caissons　（MSCs）are　conducted　under　variable　amplitude　and　asymmetrical　cyclic　loads.　The　factors　concerned　with　cumulative　displacement　and　rotation，such　as　amplitude，number　of　cycles，cyclic　order，asymmetry（two-way）are　discussed.　The　results　show　that　the　cumulative　displacement　and　rotation　of　MSCs　with　a　small　amplitude　increment　and　number　of　cycles（Δζb=0.1，N=500）are　greater　than　that　with　a　larger　amplitude　increment　and　number　of　cycles（Δζb=0.2，N=1000）under　progressively　increased　cyclic　loading;　under　asymmetric　loading（　ζc　=　-0.3　），the　cumulative　displacement　and　rotation　of　MSCs　tend　to　increase　compared　with　that　under　symmetric　loading;　under　fully　two-way　loading（　ζc　=　-1.0　），the　cumulative　displacement　and　rotation　of　MSCs　decrease　by　1/3　compared　with　that　under　unidirectional　cyclic　loading　after　changing　the　direction.　The　cumulative　displacement　and　rotation　of　MSCs　are　50%　of　regular　suction　caissons（RSCs）under　variable　amplitude　and　asymmetrical　cyclic　loading.　©　2023　Science　Press.　All　rights　reserved.