Abstract: A floor board assembly includes four base plates connected around a center plate on the same plane, a cover board covered on the center plate, four lining plates covered on the base plates, four blocking plates connected to the center plate at four sides and bridged over either two base plates and disposed in flush with the lining plates, the base plate having open blocks spaced from one another for passing electric wires through spaces therebetween, the center plate having upright rods with a respective screw holes for mounting an electric socket after the removable of the cover board, the blocking plates having rows of sharp projections for fasten the floor covering being covered over the floor board assembly.