Abstract: There are numerous cable trenches in the distribution room, and all cables in the station, except for buried cables, are laid in cable trenches. The cable trenches are widely distributed, and the equipment connected by the cables laid inside is extremely important. In the event of a fire, it is difficult for personnel to approach and there is a high risk of manual firefighting. In this paper, a special fire extinguishing device for cable trench in distribution room is developed, which consists of four parts: foam generation device, foam release device, mobile chassis, and overturning mechanism. Compressed air foam is used as the extinguishing medium to effectively deal with various fire extinguishing problems in cable trench under fire scenarios.