The invention relates to an alarm device, and specifically relates to an audible-visual alarm device used for an electric power overhauling fence. The device comprises an alarm support base, the support base is provided with two folding support legs, the lower ends of the two support legs are provided with semicircular grooves engaged with a fence pillar, the periphery of an engaging surface of the semicircular grooves is provided with a nylon Velcro used for fixing, the inner bottom surface of the support seat is provided with a semicircular recessed hole connected with a pillar head seat of the fence pillar, an alarm is arranged in a recessed hole cavity on the upper end surface of the support seat, the alarm is locked through a hinge cover plate, a control circuit of the alarm comprises a sensor U1, the sensor U1 is connected with a base electrode of a triode Q1, an emitter electrode of the triode Q1 is connected with relays K1 and K2 and an audible-visual alarm portion X1, a power supply VCC and the audible-visual alarm portion X1 are connected to form a circuit through the relay K1, and a collector electrode of the triode Q1 is connected with a button J2 and a switch J1. According to the device, the circuit structure is reasonable, the connection is reliable, and the usage requirement is satisfied.