Abstract: A large-scale model equipment was designed and made for dredged clays dewatering with ventilating vacuum method. Dewatering tests were performed on the dredged clays with initial water content being above 3 times liquid limit. The testing results showed that the volume of dredged clays can be decreased by over 30 percent with ventilating vacuum method for dewatering of 10 days, and the volume strain rate of dredged clays at the model still reaches about 3%/day when dewatering continues for one month. This paper also investigated the change law on the average water content and the deformation rate of dredged clays, as well as the suspended solids concentration of separated water from dredged clays. It was found that deformation rate has a good linear relationship with average water content, and the suspended solid concentration is very low.