The　settlement　behavior　of　soft　natural　clays　under　a　14-year　embankment　load　is　investigated　by　obtaining　the　high-quality　undisturbed　samples　of　soft　natural　clays　beneath　a　constructed　embankment.　It　is　found　that　the　conditional　way　of　determining　the　settlement　by　combining　the　layerwise　summation　method　of　calculating　settlement,　the　Osterberg　method　of　determining　the　embankment　load-induced　stress　in　subsoil,　and　the　compression　parameters　determined　from　high-quality　undisturbed　samples　overestimates　the　settlement,　compared　with　the　field　observations.　The　key　cause　is　that　the　Osterberg　method　overestimates　the　vertical　superimposed　stress　in　this　case.　The　modified　method　of　determining　the　vertical　stress　in　subsoil　suggested　by　the　authors　is　adopted　for　improving　the　accuracy　of　vertical　superimposed　stress　calculated.　The　balance　among　errors　in　the　settlement　calculation　model,　determination　of　vertical　superimposed　stress　induced　by　embankment　loads,　and　measurement　of　compression　parameters　are　also　discussed.