The invention relates to a vacuum preloading and leaching coupling cleaning type foundation treatment system. The system is used for carrying out foundation treatment on a contaminated soft foundationand site remediation on a contaminated site in the corresponding period. The system comprises a foundation sealing assembly, a vacuum preloading assembly and a soil in-situ leaching assembly; the vacuum preloading assembly comprises a vacuum preloading power mechanism, a main water pumping pipe, a water collecting pipe, vacuum preloading distribution pipelines and plastic drainage plates; the soil in-situ leaching assembly comprises a leaching power mechanism, a main injection pipe, an injection tube, leaching distribution pipelines and injection wells; the plastic drainage plates and the injection wells are arranged in the contaminated soft foundation in an inserted mode; the vacuum preloading distribution pipelines are connected to the water collecting pipe and the injection pipe; and the leaching distribution pipelines are connected to the water collecting pipe and the injection pipe. Compared with the prior art, the system has the outstanding advantages that the comprehensive engineering function can be achieved, the coupling controllability is high, vibration loading can be carried out on the contaminated soft foundation, the overall engineering construction cost can be effectively lowered, the total engineering construction period can be shortened, and the like.