An ash-residue separating and cooling device for a boiler comprises a combustion chamber, a residue control chamber, an ash-residue separating chamber, a cyclone separating device, a first ash collecting chamber, a second ash collecting chamber and a residue heat exchange chamber, wherein the lower end of the combustion chamber is connected with the residue control chamber through a residue discharge pipe, the residue control chamber is connected with the ash-residue separating chamber at the right end through an oblique residue conveying pipe, the middle of the top end of the ash-residue separating chamber is connected with the cyclone separating device through an ash conveying pipe, the residue heat exchange chamber is arranged at the lower right end of the ash-residue separating chamber, and the ash-residue separating chamber communicates with the residue heat exchange chamber through a residue passing pipe; the left end of the cyclone separating device is connected with the combustion chamber through a hot air exhaust pipe, the right end of the cyclone separating device is connected with the first ash collecting chamber through a fine ash discharge pipe, and the bottom end of the first ash collecting chamber is on the top surface of the residue heat exchange chamber; a blower device is arranged at the lower left end of the ash-residue separating chamber. The ash-residue separating and cooling device can effectively carry out separating and cooling treatment on residue generated from boiler combustion, fine ash and the residue are separated, recycling is facilitated, cold water is preheated by using heat energy in the fine ash and the residue, and energy conservation and environment protection are achieved.