The invention belongs to the technical field of activated carbon preparation, and relates to a residual energy reclaiming type device for preparing activated carbon. A combined structure on one side of an air heating furnace of the device is provided with a gas burner and a combustion fan, the other side of the air heating furnace is communicated with a partition wall heating chamber, the center of the partition wall heating chamber is vertically provided with a charcoal chamber, the bottom of the charcoal chamber is provided with a charcoal chamber bottom connecting rod mechanism in an insertion mode, the periphery of the partition wall heating chamber is wrapped by an insulating material, one side of the charcoal chamber on the middle part of the partition wall heating chamber is reserved with a space up and down and provided with two thermoelectric couples, the top end of the partition wall heating chamber is provided with a top end cover used for sealing the partition wall heating chamber, and the top end of the partition wall heating chamber passing through the top end cover is provided with a charcoal chamber gas outlet pipe and a heating chamber smoke outlet pipe respectively in a communication mode; and the charcoal chamber gas outlet pipe is communicated with the top of a tube type condenser through a three-way valve, the bottom of the tube type condenser is communicated with the air heating furnace in a pipe mode, and the middle section of a communication passage is provided with a circulating fan in series. The device has the advantages of high efficiency, simple principle, flexible implementation, energy conservation, low pollution, high charcoal yield, and the like.