Abstract: According to conditions of the soft foundation and processing requirements, this paper introduces a new high vacuum densification method(HVDM).To exame the proposed method, tests are done before soft soil foundation treatment, at the end of the soft soil foundation treatment and 5months after the end of the soft soil foundation treatment, respectively. Plate load test on the hydraulic fill sand surface is done after the construction. The results show that, the foundation soil strength is greatly improved by using HVDM.The sand layer's cone tip resistance, the side friction, and the undrained shear strength of silt layer are increased by 406.3%, 360.8% and 60.3%,respectively. The treatment effect is more obvious in the range of 6~7m deep. The physical and mechanical properties are improved to varying degrees. The dry density, is increased by 6.08%. The pore compression coefficient decreased by 8.96%. The a_1-2 decreased by 10.53%. The compression modulus of Es_1-2 increased by 12.18%. Direct shear strength increased by 8.91%. The internal friction angle increased by 41.01%. The cohesion from triaxial(UU) test increased by 33.04%. The foundation bearing capacity increased from less than 50kPa to over 120kPa, which can meet the requirements of foundation treatment.