To　protect　Chinese　ancient　building　an　ancient　rampart　in　the　Forbidden　City　was　taken　as　an　example　to　study　sinkage　of　soil　in　it　as　well　as　effects　the　sinkage　may　bring　to　the　rampart.　Considering　hole　at　different　depth　of　the　soil　as　well　as　mechanical　parameters　for　soil　and　masonry　wall,finite　element　model　of　the　rampart　was　built.3　cases　including　weight　of　soil　and　wall,live　load　and　rainwater　penetration　condition　were　considered　to　study　the　deformation,stress　and　strain　of　both　wall　and　soil　by　simulation.　Results　show　that　the　existing　holes　affect　little　to　sinkage　of　the　soil,while　rainwater　penetration　is　the　main　cause　for　sinkage　of　soil.　Thus　waterproof　work　has　to　be　done　to　solve　the　problem　besides　controlling　live　load　on　the　rampart.