The utility model provides an alarm system, wherein the alarm system consists of a voltage transformer cabinet, a monitoring control device and an alarm circuit, wherein the voltage transformer cabinet comprises a primary side and a secondary side, the primary side is connected with an incoming line end of a high voltage power supply circuit, and the secondary side is connected with a low voltage power supply circuit; the monitoring control device is connected on the low voltage power supply circuit close to the secondary side and used for sending control messages when in monitoring of power failure or voltage loss at the incoming line end of the high voltage power supply circuit; and the alarm circuit is used for receiving the control messages and sending alarm according to the control messages. The alarm system of the embodiment of the utility model provides an alarm mode for the power failure or voltage loss at the incoming line end of the high voltage power supply circuit, solves the technical defect that the existing alarm system only can carry out alarm occurred at the load side of the high voltage power supply circuit, and realizes the purpose of carrying out alarm on the power failure or voltage loss occurred at the incoming line end of the high voltage power supply circuit.