The invention discloses a drainage reinforcing method for an ultra-fine tailings deposited beach. The method comprises the steps that drainage pipes are laid from the outside to the inside of a starter dam along a mountain; seepage drainage pipes are longitudinally laid on the deposited beach along the mountain, and the seepage drainage pipes and the drainage pipes are connected to form a water guide system; transverse slotted seepage drainage plates are laid in the deposited beach, and the two ends of each transverse slotted seepage drainage plate are connected with the longitudinal seepage drainage pipes laid along the mountain; floats connected with the transverse slotted seepage drainage plates are placed on the portion, below the transverse slotted seepage drainage plate, of the deposited beach; longitudinal slotted seepage drainage plates are laid along a tailings pond mountain slope up and down, and the lower ends of the longitudinal slotted seepage drainage plates are connectedwith the seepage drainage pipes; ore is placed in a tailings pond to fill the gaps of the transverse slotted seepage drainage plates and make the beach surface flat, double-layer transverse slotted seepage drainage plates continue to be laid on the beach surface, and the two ends of double-layer transverse slotted seepage drainage plate are connected with the longitudinal slotted seepage drainageplates laid along the mountain; and floats are connected with the lower portions of the double-layer transverse slotted seepage drainage plates. The method is simple in construction, good in stability and good in drainage effect, the strength of the deposited beach is effectively improved, and the construction cost is low.