During the reinforcement of the newly-filled or weak ground, the sealing trench is often used to seal the boundary. But, for the permeable and breathable soil, the application of sealing trench for the boundary sealing during large -area vacuum preloading treatment is neither economical nor effective. Considering the breathable soil, engineering cost and construction period, we adopt a new technology to seal the boundary by a combination of sealing trench in sections and clay sealing wall in the whole region. It’s shown that the technology possesses an obvious effect on the soft soil foundation and has achieved very good economic benefit.