The invention provides a special-purposed brake apparatus of a cable pay-off rack. The brake apparatus comprises a pedestal, the pedestal is provided with a friction mechanism for friction of a roller of the cable pay-off rack, one end of the friction mechanism is hinged to the pedestal, and the other end of the friction mechanism is driven to move up and down by an elevating mechanism. The brake apparatus can be used to control the pay-off speed effectively, and prevent problems including that leads are wound and the pay-off rack is pulled down due to the fact that brake is not timely; and the brake apparatus is provided with a locking mechanism which further ensure the personnel safety of users.