A　laboratory　simulation　method　is　used　in　this　study　to　examine　the　effect　of　marine　environment　on　the　strength　of　cemented　soil　mixed　with　composite　ferronickel　slag　powder.　In　the　experiment,　ferronickel　slag　powder　and　mineral　powder　were　mixed　into　admixture,　and　then　added　to　a　cemented　soil.　Through　erosion　analysis,　unconfined　compression　tests,　and　SEM　and　EDS　test　analysis,　the　influence　of　marine　environment　on　the　apparent　characteristics,　strength　and　micro-morphology　of　this　modified　cemented　soil　was　studied.　Results　show　that　in　marine　environment,　the　modified　cemented　soil　is　eroded　and　its　strength　deteriorated.　And　its　erosion　degradation　is　intensifying　over　time.　However,　its　component　of　composite　ferronickel　slag　powder　has　good　durability　with　micro　aggregate　effect　and　active　effect.　Thus,　this　type　of　composite　powder　can　not　only　improve　the　strength　performance　of　cemented　soil　but　also　reduce　its　erosion　in　marine　environment　and　alleviate　its　strength　deterioration.　©　2020　All　right　reserved.