The invention discloses a combined treatment method for reclaiming land from the sea. The combined treatment method comprises following steps: A, extracting slurries and injecting slurries with flocculating agents and/or lime; B, inputting slurries into a stirrer for uniform stirring; C, inputting uniformly-mixed slurries into a vacuum pre-loading slurry pool; C, equipping the vacuum pre-loading slurry pool with vertical drainage boards, connecting upper ends of the vertical drainage boards to an drainage pipeline which is connected with the outside, covering the top of soil in the vacuum pre-loading slurry pool and the drainage pipeline with sealing cloth, adopting a sealing structure and soil sealing for the edge of the sealing cloth, connecting a vacuum pump with the drainage pipeline for extracting water in soil. The combined treatment method for reclaiming land from the sea has following beneficial effects: 1, the drainage boards are not easily blocked; 2, soil bearing capacity after processing is increased and sedimentation is reduced.