Isotropic　consolidation　test　and　consolidated-undrained　triaxial　test　were　first　undertaken　to　obtain　the　parameters　of　the　modified　cam-clay　(MCC)　model　and　the　behavior　of　natural　clayey　soil.　Then,　for　the　first　time,　numerical　simulation　of　the　two　tests　was　performed　by　three-dimensional　finite　element　method　(FEM)　using　ABAQUS　program.　The　consolidated-drained　triaxial　test　was　also　simulated　by　FEM　and　compared　with　theoretical　results　of　MCC　model.　Especially,　the　behaviors　of　MCC　model　during　unloading　and　reloading　were　analyzed　in　detail　by　FEM.　The　analysis　and　comparison　indicate　that　the　MCC　model　is　able　to　accurately　describe　many　features　of　the　mechanical　behavior　of　the　soil　in　isotropic　consolidation　test　and　consolidated-drained　triaxial　test.　And　the　MCC　model　can　well　describe　the　variation　of　excess　pore　water　pressure　with　the　development　of　axial　strain　in　consolidated-undrained　triaxial　test,　but　its　ability　to　predict　the　relationship　between　axial　strain　and　shear　stress　is　relatively　poor.　The　comparison　also　shows　that　FEM　solutions　of　the　MCC　model　are　basically　identical　to　the　theoretical　ones.　In　addition,　Mandel-Cryer　effect　unable　to　be　discovered　by　the　conventional　triaxial　test　in　laboratories　was　disclosed　by　FEM.　The　analysis　of　unloading-reloading　by　FEM　demonstrates　that　the　MCC　model　disobeys　the　law　of　energy　conservation　under　the　cyclic　loading　condition　if　the　elastic　shear　modulus　is　linearly　pressure-dependent.