The invention discloses a sewage processing system, which at least comprises a sewage tank for storing sewage; a filter, which is installed under the level surface of the sewage in the sewage tank; aclean water tank for storing filtered clean water; and a water pump, which is connected to the water outlet end of the filter through a water inlet pipe. The water pump is also connected to a water outlet pipe that is communicated with the clean water tank. The filter comprises a shell. Multiple filter cores are arranged on the shell. The shell is rotatingly connected to a rotary valve. The rotaryvalve is provided with a water inlet valve spool that is communicated with the sewage tank and one filter core and a water outlet valve spool that is communicated with the filter core and the water pump. Multiple filter cores are mounted in the filter, when one filter core is obstructed, the water path can be switched so as to filter sewage by another filter core, and the maintenance frequency ofthe system is obviously reduced.