The invention belongs to the field of testing control devices, and particularly relates to a magnetic-electric rotational-speed sensor capable of realizing hot-redundancy of devices. The magnetic-electric rotational-speed sensor comprises a permanent magnet, a first independent induction coil, a second independent induction coil, a signal processing circuit and a sensor shell. The first independent induction coil and the second independent induction coil are wound on the permanent magnet and fix the permanent magnet into the sensor shell, the axis of the permanent magnet is coincided with the central axis of the sensor shell, the two independent induction coils are respectively connected with the signal processing circuit, holes are arranged in centers of two ends of the sensor shell, the end of the sensor shell close to the signal processing circuit is used for leading out a conducting wire, and the other end of the sensor shell is used for receiving detection signals. The magnetic-electric rotational-speed sensor can work normally assuredly even if the optional coil fails, reliability of the magnetic-electric rotational-speed sensor is greatly improved, and reliability of measured objects such as diesel engines, gasoline engines and gas turbines is also improved.