Abstract: In the process of vacuum preloading consolidation, soft foundation is consolidated by powerful vacuum suction. A kind of soft clay has many fine particles that would be flowed to drain pipes with vacuum. The plastic pipes would be surrounded with clay. Then they would be formed with mud membrane. Through laboratory test, the course of drainage consolidation is simulated. It is aimed that the laws of particle migration can be resolved with the proposed approach. Test results confirm that the consolidation conditions affect the fine particle migration phenomenon. At the gravitational compaction consolidation stage, the fine particles are influenced by boundary conditions and seepage paths. However, at the pressure consolidation stage, the fine particles are influenced by the additional loading generated vertical pressure. Therefore, the tendency of particle migration is no more than weak. And The distribution of fine particles is changed from vertical gershgorim band to horizontal gershgorim band. Furthermore, the mass ratio of silt and clay is primary defined as aggregate clay ratio. It reflects the status of migration process. The aggregate clay ratio is considered as the indicator of migration. Data analysis results show that the indicator can effectively reflect the degree of consolidation. With the continuing process of consolidation drainage, the aggregate clay ratio is increasing gradually. It reflects indirectly the strength of high clay dredger fill. In the consolidation process, aggregate clay ratio is increased as the drainage velocity is changed lower.