The invention discloses a novel cable antimagnetic alarm device which is composed of a device body. The device body comprises a semiconductor buffer layer, a PE insulating sleeve layer, an aluminum sleeve layer and a bar clasp, wherein the semiconductor buffer layer, the PE insulating sleeve layer, the aluminum sleeve layer and the bar clasp successively sleeves a cable from inside to outside. A bottom support is arranged outside the bar clasp. A power supply, an electromagnetic radiation interference detector and an anti-interference filter are embedded in the bottom support. The electromagnetic radiation interference detector and the anti-interference filter are connected with the power supply. The terminal of the electromagnetic radiation interference detector is connected with the aluminum sleeve layer. The anti-interference filter is serially connected with the inlet end of the cable. The novel cable antimagnetic alarm device has advantages of shielding electromagnetic interference, eliminating cable grounding interference, reducing distortion factor of a transmitted signal, and ensuring long-distance transmission effect of an electric signal.