The invention provides a cable synchronous separating and tensioning device which comprises a rotary mechanism, a transverse moving mechanism, a cable fixing table and a fixed bottom plate. The transverse moving mechanism comprises a movable support, a movable slider, a lead screw and a first motor. The support is fixedly arranged on the fixed bottom plate. The movable slider is arranged on two guide slide rods on the movable support through two through holes in the movable slider in a sleeving mode. The lead screw is sleeved with one threaded hole in the movable slider. The first motor is fixed to one end of the support and connected with one end of the lead screw. The rotary mechanism is arranged on the movable slider. The cable fixing table is arranged on the fixed bottom plate and located at the front end of the rotary mechanism. Cable cores can be separated by means of the rotary mechanism and can be tensioned by means of the transverse moving mechanism in the cable core separating process, and therefore the separation efficiency is high and the separation quality is ensured when the cable synchronous separating and tensioning device is used for separation work of the cable cores.