A drying device for a wood-waste collecting machine includes a blower set on the base of the machine and a heating member connected between the blower and the conveying device of the machine. The blower has an air outlet connected with a windpipe, and the heating member is connected with one end of the windpipe, having a tubular member and a heating element in the tubular member. Between the other end of the heating member and a preset sidewall of the container of the conveying device is provided a pipe joint, for air sucked by the blower blown in the heating member to heat. Then heated air is blown through the air holes of the sidewall of the collecting chamber of the container of the conveying device to dry wood waste therein and then compressed in the compressing device of the machine to become tight solid blocks.