Abstract: There are problems when dealing with the dredger fills using the traditional vacuum preloading method, for example, the treated area can not be too large and the plastic-sheet maybe leaks. To solve these problems, the new sheet-free vacuum preloading method is proposed, in which the mud-covering replaces the plastic sheet. This method can improve the treated area, save the cost of plastic sheet and solve the problem of piling up dredger fills. In order to investigate the effect and influence factors of the new vacuum preloading method, laboratory model tests and numerical simulations are carried out. The displacement of soil, the change of pore water pressure at the specific location and the settlement of soil surface in different loading modes are studied. The conclusions are that the effect of the sheet-free vacuum preloading method on the soft soil foundation treatment is good, and the effect of the treatment can be improved by the way of graded loading. The numerical simulation software PFC^2D is used to study the movement of soil particles in the process of sheet-free vacuum preloading. The results show that under the vacuum pressure, the soil particles mainly gather towards the PVDs. It can reduce the clogging of PVDs by graded loading to get better treatment effect.