The invention relates to the field of fire emergency, and particularly relates to a fire alarm device based on a fire emergency system. The fire alarm device comprises a main body device, a fixing device, a replacing device and a cleaning device, the main body device comprises a fixing plate, an alarm, a temperature sensor and a smoke sensor, and the left side of the top end surface of the fixing plate is fixedly connected with a battery. In the invention, by arranging a first handle, a first threaded shaft, a sliding plate and a suction cup, during use, the first handle is rotated to drive the first threaded shaft to rotate, the first threaded shaft rotates to drive the sliding plate to slide, the sliding plate slides to drive a first hole to move, the first hole, a second hole and the suction cup are staggered, an air inlet channel of the suction cup is closed, and then a fixing plate is pressed on a wall; and the fixing plate can be firmly adsorbed and fixed on a wall under the action of the suction cup, and the fire alarm device is installed so that the installation process of the fire alarm device is simple and convenient, and time and labor are saved.