The invention discloses a specialized device and a method for laying a secondary cable. The specialized device comprises a support body and a nut, wherein the support body is a ring-shaped body with a notch; the ring-shaped body is supported on a support rod; external threads are arranged on the lower part of the support rod and is locked by the nut. The support rod downwards penetrates through a hole corresponding to a cable rack, the support body is locked on the cable rack through the nut, the secondary cable is then laid, the secondary cable is embedded into a ring-shaped inner cavity through the notch of the ring-shaped body of the support body when being laid, and the secondary cable is located through a ring wall of the ring-shaped body. The specialized device for laying the secondary cable is simple in structure and convenient to use.