Abstract: In view of the deep soft foundation in Zhuhai,the vacuum combined loading preloading method is used to reinforce the soft foundation.During the construction process,the surface settlement,the vacuum under the membrane,the pore water pressure and the deep horizontal displacement of the soft foundation are monitored,and obtained the time dependent curve of the vacuum preloading to consolidate the soft soil foundation.After the soft foundation treatment was completed,the original soil was subjected to the vane shear tests and the load tests,and laboratory soil tests was also used in the soil.Analysis results show that physical and mechanical properties of reinforcement of the soil have been significantly improved,foundation reinforcement effect is good,the influence depth reaches to 25m~30m,and the reinforcement effect is the most significant in the range of 15 m~20 m; But the vacuum preloading does not change the thixotropy of the soft soil,and the soft soil should still avoid the disturbance after reinforcement.