The invention discloses a spray device and a spray method. The spray device comprises a spray cavity and spray nozzles, wherein the spray nozzles are arranged on two side walls of the spray cavity; and the two side walls in the spray cavity are equipped with guide plates which are inclined downwards and are staggered with each other. According to the spray device disclosed by the invention, the guide plates which are staggered with each other are arranged in the spray cavity, and a spray treatment process can be prolonged while reflowed sewage is treated, so that the spray treatment effect is improved. The spray device has the advantages of being simple in structure, convenient to manufacture and obvious in effect.