The invention discloses a wire rope on-line detector, comprising a dead lever, Hall sensors and displacement sensors. A cross bar is in a pin joint relation with location holes on the dead lever. A fixed part is provided with a rope aperture on an axle center thereof; the Hall sensors are arranged in a cavity in the middle of the fixed part; the rope aperture passes through the cavity in the middle of the fixed part; the Hall sensors are uniformly distributed on periphery of the wire rope; the fixed part is fixed on the dead lever. A connection rack is equipped with positioning wheels with displacement sensors on two ends thereof, and is fixed above the fixed part; an upper part of a spring is clinging to the cross bar, and a lower part of the spring is embedded into spring apertures on the fixed part and is in an elastic contact with the Hall sensors. A lower part of the dead lever is in bolt joint relation with a pedestal. In the invention, a dead lever structure is employed to fix the fixed part, Hall sensors arranged in the cavity of the fixed part and the connection rack on the dead lever; besides the lower part of the dead lever can be fixed on any pedestal conveniently to carry out real-time detection at any time, without manual hand-holding.