The invention discloses an expanding rescue device for a ruin channel. The expanding rescue device comprises three face expanding units, wherein the face expanding units are mutually hinged into a triangular mechanism through a supporting shaft and a supporting block; an expanding mechanism is connected in series to a lead screw; the lead screw is fixedly connected with a motor; a forward slide block and a backward slide block are arranged in a guide groove; and one end of a connecting rod is hinged with a slide block hinging hole, and the other end of the connecting rod is hinged with a connecting rod which is hinged with the forward slide block and a connecting rod which is hinged with the backward slide block. When the expanding rescue device is used, the motor is used for driving the lead screw to rotate, the forward slide block and the backward slide block are driven to move away from each other firstly, and the slide blocks are used for driving the supporting block to be folded; and after the three face expanding units are folded, the motor stops running, is put into a ruin gap and is restarted to run in a direction opposite to the folding direction, the forward slide block and the backward slide block move towards each other, and the ruin gap is expanded into a channel with a large section, so that the functions of transporting rescue materials and rescuing wounded persons are realized. The expanding rescue device has the advantages of high rescue work efficiency, low risk and high reliability.