The utility model relates to an incinerator for waste liquid, which belongs to the purifying device field of the heat recovery after the incineration of the waste liquid of chemical industry and papermaking industry. The utility model is mainly composed of a waste liquid incinerator and a waste heat boiler, wherein the waste heat boiler is formed by welding a horizontal vertical header tank, a horizontal transverse header tank, a heat exchange tube bank, a dropping tube, a rising tube and a steam dome to form a water circulating system with a communicated inner chamber and the water circulating system is also used as a boiler body framework. An inspection channel is arranged between the groups of solidified slag tube banks, and a dust cleaning boiler door, a dust blowing device, a dust bucket and a dust cleaning window are arranged on the boiler body. The waste heat boiler has the advantages of simple structure, light weight and small size; the heat exchange efficiency of the heat exchange tube bank is obviously increased; the solidified slag tube banks with large intervals are used for effectively preventing the slagging and bridging between the tubes so that the tube banks only generate loose smutch which is easy to clean; the dust cleaning work is simple with high efficient, and continuous operating time is prolonged from the primary only one week to three months. The utility model can use the waste heat to generate hot water, steam and hot wind, and can satisfy the environmental protection requirement of the waste liquid incineration under various loads.