Two sets of waste water treatment processes are put forward in this paper for the fuel ethanol plant with cassava as raw materials.Some conclusions are obtained after comprehensive comparison of these two processes and thorough analysis based on considerations of economization,consumption and generation of energy.These conclusions can be used as a guide line for the construction and modification of a waste water treatment station in the fuel ethanol plant,which will facilitate high efficiency utilization,energy saving and consumption reduction on all factors of production.