The invention discloses an alarming device for a wire cutting machine spindle. The alarming device comprises guide rods, an alarming rod, a first broken wire detection unit, a relay unit, a PLC and an alarming unit, wherein the guide rods are arranged at the two ends of the wire cutting machine spindle; the two ends of the alarming rod are respectively fixed on the guide rods; the first broken wire detection unit is arranged at one end of the wire cutting machine spindle; the relay unit, the PLC and the alarming unit are arranged in a control cabinet of the wire cutting machine; the relay unit is electrically connected with the first broken wire detection unit; the wire cutting machine is integrally connected with a power cathode; the alarming rod is connected with a power anode; under a normal condition, the relay unit can continuously send a signal to PLC through a normally-closed contact; when the wire net of the wire cutting machine is broken, the broken wire head falls onto the alarming rod, the whole wire cutting machine and the alarming rod are formed into a circuit loop, the signal is sent to the relay unit through the first broken wire detection unit, the normally-closed contact of the relay unit is disconnected and the PCL cannot receive the signal sent by the relay unit, so that the alarming unit is controlled to alarm. The alarming device utilizes the circuit connection/disconnection principle to alarm, so that the alarming is higher in reliability and is more sensitive.