This utility model relates to the field of incinerator technology and provides a vertical waste treatment incinerator, including a furnace body; a feeding structure located on the side wall of the furnace body; and a slagdischarge structure located at the lower part of the furnace body. The slagdischarge structure includes a slagdischarge channel located on the outer side wall of the furnace body, and an annular heat absorption groove is provided on the outer side of the slag discharge channel, which is filled with a heat source for heat absorption. A drying chamber and a fan are sequentially arranged on the upper part of the furnace body adjacent to the slag discharge channel. By setting an annular heat absorption groove and heat-conducting plates on the outside of the slag discharge channel, this utility model can not only efficiently recover the heat released during the slag discharge process for drying the waste about to enter the incinerator, thereby improving incineration efficiency and reducing external energy input, but also effectively extend the service life of key system components and maintain the stability and energy utilization efficiency of the system by reducing the temperature of the slag discharge channel, preventing heat backflow, and ensuring the safe discharge of ash and slag.