NOVELTY - Coupled ethanol-methane dual thick mash fermentation process for cassava raw material mash crude filtrate, comprises smashing cassava raw materials; mixing with process water; removing sand; liquefying and saccharifying; fermenting thick mash; distilling; refluxing crude filtrate and filtering the rest crude filtrate; removing the sand; separating the obtained methane, and carrying out plate-frame separation on the residual liquor; separating the obtained organic fertilizer, and carrying out secondary anaerobic treatment on the residual liquor; carrying out aerobic treatment.    USE - The method is useful for coupled ethanol-methane dual thick mash fermentation process for cassava raw material mash crude filtrate (claimed).    ADVANTAGE - The fermentation process greatly reduces the yield and discharge of sewage, and alleviated environmental protection pressure and treatment capacity.    DETAILED DESCRIPTION - Coupled ethanol-methane dual thick mash fermentation process for cassava raw material mash crude filtrate, comprises (i) smashing cassava raw materials; (ii) adding process water and mixing; (iii) removing sand, namely separating the obtained pure sand; (iv) liquefying and saccharifying; (v) fermenting thick mash; (vi) distilling by separating the obtained ethanol product and causing residual liquor to enter into a wine slot; (vii) causing crude filtrate obtained by virtue of plate-frame separation to reflux into the step (ii) and the rest crude filtrate to enter into a slot pool to be filtered; (viii) removing the sand by separating the obtained pure sand and carrying out thick mash anaerobic fermentation on the residual liquor; (ix) separating the obtained methane, and carrying out plate-frame separation on the residual liquor; (x) separating the obtained organic fertilizer, and carrying out secondary anaerobic treatment on the residual liquor; (xi) carrying out sequencing batch reactor (SBR) aerobic treatment; and (xii) causing the residual liquor to enter into a sewage treatment plant.