A sectionalized roller device for square billet continuous casting is mainly used for continuously casting an upper sectionalized roller and a lower sectionalized roller of a first section of a fan-shaped section. Spindle heads at the left end and the right end of the first upper sectionalized roller positioning central spindle and a circular arc of an upper positioning seat conduct positioning in a matched mode, the upper positioning seat and a press cover compress the spindle heads at the two ends of the first positioning central spindle, spindle heads at the left end and the right end of a second lower sectionalized roller positioning central spindle and a circular arc of a lower positioning seat conduct positioning in a matched mode, and the left spindle end and the right spindle end of the second positioning central spindle limit the second positioning central spindle to conduct axial movement and radial rotation by using clamping plates, second bolts and second spring washers; and the left side and the right side of each of the upper positioning central spindle and the lower positioning central spindle are connected with a roller shell through elastic bearings, and the positioning central spindles are internally provided with lubricating oil and cooling water channels. According to the sectionalized roller device for square billet continuous casting, the cooling water channels and lubricating oil channels are formed in the sectionalized roller device, mounting is convenient and rapid, the sectionalized rollers are high temperature resistant and fatigue resistant and have high wear resistance, and the maintenance time can be shortened.