The invention provides a sewage processing method, solving the problems of unsatisfactory effect of the sewage processing and the existing dead end of the sewage processing in a prior technology. The method comprises the following steps: adding medications into the sewage; flowing the mixed liquor into a cyclone reactor tangentially to perform cyclone separate; performing magnetic separation process on the mixed liquor after being cyclone separated through a magnetic roller. Meanwhile, the invention also provides a sewage processing device adopting the method; the device consists of a sewage inlet pipe, a clear water outlet pipe, a medication-adding system, a cyclone reactor, a magnetic roller and a scraper. The medication-adding system is connected with the sewage inlet pipe; an outlet end nozzle of the sewage inlet pipe is connected tangentially into the cyclone reactor, the cyclone reactor is a revolving body, the magnetic roller and the scraper are positioned in the cyclone reactor, the magnetic roller and the cyclone reactor are arranged on a same axial-line, and the scraper is used to scrape ferromagnetism mud cluster which is absorbed magnetically on the magnetic roller. In the invention, sewage purification has a good effect, the yielding water is clear, sewage processing method and sewage processing device of the invention are applicable to processing the sewage and the sewage containing grease and mud.