Special independent type, photoelectric detection means, has a built-in alarm integrated circuit, can automatically analyze and detect the fire smoke, and a strong warning signals, with more than 85 decibels of sound output, so that people know as early as possible fire. The infrared scattering principle is adopted to meet the requirement of environmental protection. The battery can last up to one year with a 9V battery or 220V power supply, and has the effect of the coupling of a high-quality loudspeaker. Stable and reliable performance, beautiful appearance, unique structure design, easy installation and use.