The utility model relates to the hot-rolling mill field, in particular to a vertical roll of a hot-rolling mill. A vertical roll provided with cooling water retaining devices comprises a roll body and a bearing support, wherein a pair of water retaining devices are mounted symmetrically on the bearing support, and brushes arranged on the water retaining devices are respectively jointed with the two sides of the working plane of the roll body. Due to the water retaining devices arranged on the two sides of the working plane of the roll body, a small amount of cooling water brought out during the rotation of the vertical roll is retained through the water retaining devices before contacting a strip steel, so ferrite of the rolling strip steel can not be separated out due to regional hypothermia, and the quality defect of burr is avoided; and the contact type and distance between the water retaining device and vertical roll can be adjusted freely according to the requirement, so convenient and reliable usage is achieved, and the quality of the end product is efficiently improved.