The　modified　suction　caisson　(MSC)　adds　a　short-skirted　structure　around　the　regular　suction　caissons　to　increase　the　lateral　bearing　capacity　and　limit　the　deflection.　The　MSC　is　suitable　for　acting　as　the　offshore　wind　turbine　foundation　subjected　to　larger　lateral　loads　compared　with　the　imposed　vertical　loads.　Determination　of　the　lateral　bearing　capacity　is　a　key　issue　for　the　MSC　design.　The　formula　estimating　the　lateral　bearing　capacity　of　the　MSC　was　proposed　in　terms　of　the　limit　equilibrium　method　and　was　verified　by　the　test　results.　Parametric　studies　on　the　lateral　bearing　capacity　were　also　carried　out.　It　was　found　that　the　lateral　bearing　capacity　of　the　MSC　increases　with　the　increasing　length　and　radius　of　the　external　skirt,　and　the　lateral　bearing　capacity　increases　linearly　with　the　increasing　coefficient　of　subgrade　reaction.　The　maximum　lateral　bearing　capacity　of　the　MSC　is　attained　when　the　ratio　of　the　radii　of　the　internal　compartment　to　the　external　skirt　equals　0.82　and　the　ratio　of　the　lengths　of　the　external　skirt　to　the　internal　compartment　equals　0.48,　provided　that　the　steel　usage　of　the　MSC　is　kept　constant.