In order to improve the rapid treatment method for high water content mud，a novel treatment method was proposed.The chemical flocculation，vacuum preloading and secondary ash mixing were combined in the method，the test was performed to verify the effect. The results show that the water content of slurry added with 1% polyaluminium chloride decreases from 300% to 100% after one day of flocculation sedimentation. And the water content can decrease to 40.52% by vacuum preloading. Furthermore，the moisture content of the slurry will decrease to 35.40% after the secondary ash mixing modification treatment，the treatment slurry can be plasticized at this time. The unconfined compressive strength can exceed 60 kpa，meeting the bearing capacity requirement of ordinary foundation. The traditional treatment method of dredged slurry will take 2 ~ 3 years，only 4 ~ 5 days are needed using the proposed method. The construction period will be cut down significantly. Those indicates the combined treatment is an efficient，low-cost and rapid method to reduce the water content of slurry.This method can provide reference for similar projects.