A horizontal-vertical drain board-flocculation vacuum preloading sediment treatment method, including (1) electro-osmotic electrodes disposed on the top and bottom of each reinforcing bar of the reinforced frame; (2) after the sediment is blown to the bottommost layer of vacuum preloading tank, the support is fitted over each reinforced frame, and the clips are fastened; (3) the transverse drain board passes through the support, one end of transverse drain board is connected to a curved tube; (4) repeat Step 2 and Step 3 until the sediment is blown to the surface layer of vacuum preloading tank; (5) a vertical drain board is arranged vertically between two adjacent rows of reinforced frames; (6) the curved tube is connected to the first junction block through the second junction block, and then the geotextile and sealing film are laid, the vacuum pump and power supply are switched on at last.