The invention discloses a cable tray paying-off device. The cable tray paying-off device comprises a base. A groove extending back and forth along the length direction of the base is arranged in the upper portion of the base, a cavity communicated with the groove is arranged in the base, a carrying roller is mounted in the middle portion of the cavity through a rotating shaft extending left and right, a front driving wheel and a back driving wheel are respectively mounted at the front end and the back end of the carrying roller in the cavity through a positioning device, the outer periphery top of each of the front driving wheel and the back driving wheel is slightly higher than that of the carrying roller, the front driving wheel is in transmission fit with the back driving wheel through a belt, a motor in transmission fit with the front wheel is further mounted in the cavity, the front and back ends of the base is respectively provided with a sloping desk, each of the sloping desks is provided with a vertically-penetrating through hole, a positioning rod is inserted in the through hole, and a roller is mounted at the upper end of the positioning rod. The cable tray feeding device is reasonable in structure, free from overturning of a cable tray, capable of realizing paying off by only rolling the cable tray and simple and laborsaving in operation, at most one person is enough to stay with the cable tray during paying off, and paying-off efficiency can be greatly improved.