The invention discloses a water overflow preventing type floor drain, and relates to the technical field of manufacturing of water draining devices. The water overflow preventing type floor drain comprises a casing and a cover plate, wherein water drain holes are distributed in the cover plate; the casing is provided with a water collecting cavity and a water drain cavity, and the water drain cavity is positioned under the water collecting cavity; a support separating plate is arranged between the water drain cavity and the water collecting cavity; a water outlet groove is formed in the support separating plate; a floating sealing plate is arranged in the water drain cavity, and is hung on the support separating plate by a slide rod. Compared with the prior art, the water overflow preventing type floor drain has the advantage that in the use process, when the water in a water drainage pipeline system is not smoothly drained, the sewage in the water drain pipe overflows onto the water drain cylinder, the floating sealing plate is jacked up, and the upper end of the floating sealing plate is attached to the support ring plate, so that the overflow of sewage onto ground is prevented, the easiness in damage of the slide rod is avoided, and the service life is long.