A dry dock floor floating layer for immersed tunnel pipe section floating is characterized in that a foundation of a dry dock pipeline prefabricating area is filled with a medium-coarse sand inverted filtering layer in a changing manner; a concrete cushion layer is laid on the medium-coarse sand inverted filtering layer; lattice stalk sleeper beams are arranged on the concrete cushion layer; the part between every two adjacent lattice stalk sleeper beams is filled with a graded broken stone layer; and plain concrete plates are poured above the graded broken stone layers, each plain concrete plate is provided with three longitudinal water filtering grooves evenly distributed and transverse water filtering grooves, and the water filtering grooves are filled with grain stone. On the dock floor changing and filling foundation, the broken stone layer is arranged between every two adjacent pipe section foundation bottom floating layer stalk beams, the water filtering grooves are formed in the topmost plain concrete plates in the longitudinal direction and the transverse direction and are filled with the grain stone, and therefore the requirement for flatness of a floating layer can be met, and the requirement for pipe section floating water passing performance can also be met. In the pipe section floating stage, after a dry dock is filled with water, the water filtering grooves can become a water inlet channel, water can pass through the pipe section bottom water filtering grooves and rapidly enters the bottom of a pipe section, and the pipe section smoothly floats.