A cable sample reserving device for a nuclear power station comprises a fixed sample reserving ring, a sample reserving ring fixing device, a synchronization rod A, a main supporting frame, a manual control rod, wheels, a connecting rod, a fixing piece, a movable sample reserving ring and a synchronization rod B. The sample reserving ring fixing device comprises a fixing device operation rod and a fixing rod. The main supporting frame plays a supporting effect, parts are assembled on the main supporting frame, the main supporting frame is connected with the wheels through bearings, and the wheels slide on tracks, so that the whole device slides along the tracks. The fixed sample reserving ring and the movable sample reserving ring are used for an electric wire for testing to be put on, the fixed sample reserving ring is fixed to the main supporting frame and is non-movable, and the movable sample reserving ring is connected with the main supporting frame through the fixing piece and can rotate with the synchronization rod B as a shaft. The sample reserving ring fixing device is used for fixing the movable sample reserving ring in a fixed working state. The synchronization rod A, the manual control rod, the wheels, the connecting rod, the fixing piece and the synchronization rod B form a four-rod mechanism which is used for operating lifting of the movable sample reserving ring.