The utility model discloses a street lamp fault automatic alarm device. The device comprises a box body, a box door, a base and a mounting plate, the box door is hinged to one side of the outer wall of the box body, the base is fixedly arranged at the bottom of an inner cavity of the box body, the mounting plate is arranged on one side of the top of the base, an automatic alarm host is fixedly arranged on the surface of the top of the base, and an input port is fixedly formed in the surface of one side of the top of the mounting plate. According to the utility model, when an external street lamp breaks down; a transmission line for controlling and connecting the faulty street lamp is short-circuited; the corresponding output port transmits the short-circuit signal to the automatic alarm host; and then, the automatic alarm host can feed back a signal to the system, so that a worker can be reminded of coming for maintenance, and the automatic alarm host can control a fault indicator lampabove a faulty output port to flicker, so that the maintenance personnel can quickly determine the fault position, and the system is suitable for being widely popularized and used.