The effectiveness of fire suppression is strong. Ultra-fine dry powder self-fire device can be applied in the distribution room of the power distribution cabinet, cable trench, cable interlayer, communication station and other unattended and traditional means can not solve the place, can achieve passive start, can be in the early stage of fire extinguishes the fire, to achieve early suppression to reduce losses. For example, the internal environment of cable tunnel, cable interlayer and cable shaft is generally narrow, or the length is long, the height is high, the support is dense and the conditions are complex. This device is particularly suitable for similar sites where many piped fire extinguishing systems are difficult to function.