Air-breathing smoke-sensing fire alarm system

The utility model relates to the field of fire alarm, and discloses an air-breathing smoke-sensing fire alarm system which comprises an outer shell, an air inlet hole and an air outlet hole are formed in the outer circle face of the outer shell, a sealing disc located between the air inlet hole and the air outlet hole is coaxially arranged in the outer shell, and the end face, facing the air inlet hole, of the sealing disc extends to form a conical sleeve. The conical sleeve is in a circular truncated cone shape with two open ends, the diameter of the conical sleeve is gradually reduced in the axial direction of the sealing disc and in the direction from the air inlet hole to the air outlet hole, a connecting hole communicated with the conical sleeve is formed in the end face of the sealing disc, a support body is arranged in the conical sleeve, and a sensor is arranged on the support body; air is actively pulled to enter the outer shell through the fan and is exhausted from the air outlet holes, a fire can b