The invention discloses a fire alarm for municipal engineering construction. The fire alarm comprises a central processing unit and an external box body, a water spraying mechanism, a smoke alarm, a camera and a dry powder extinguisher are arranged in the external box body, the smoke alarm is fixedly connected with the external box body, and the smoke alarm is electrically connected with the central processing unit. According to the fire alarm for municipal engineering construction, through cooperation of the central processing unit, the water spraying mechanism, the smoke alarm, the camera, arotating piece, a control mechanism, the dry powder extinguisher and other mechanisms, when a fire occurs, whether a circuit catches fire or not can be judged firstly, then water spraying or dry powder spraying is decided, and the possibility of electric shock is reduced; and moreover, professionals can remotely control the fire extinguisher to spray dry powder, so that the time is saved, the fire can be accurately controlled, and the problems that electric power is possibly leaked when water is directly sprayed in case of a fire, the danger of electric shock of people is increased and the rescue difficulty is increased are solved.