NOVELTY - Pretreatment system of anaerobic fermentation raw material comprises a pretreatment tank (5) filled with anaerobic fermentation raw material and used for diluting, agitating, settling and delaminating the fermentation raw material to separate the anaerobic fermentation raw material into a floated residue on an upper layer, nutrients on a middle layer and settled sand on a lower layer. A barrier ditch (8) is interconnected with the pretreatment tank and used for filtering out the floated residue from the upper layer floated residue and nutrient middle layer in the pretreatment tank.    USE - Used as a pretreatment system of anaerobic fermentation raw material.    ADVANTAGE - The device: solves purification problems of raw materials of anaerobic fermentation of biogas production and large subsequent treatment load, increases utilization rate of raw materials, and reduces operational costs.    DETAILED DESCRIPTION - Pretreatment system of anaerobic fermentation raw material comprises a pretreatment tank (5) filled with anaerobic fermentation raw material and used for diluting, agitating, settling and delaminating the fermentation raw material to separate the anaerobic fermentation raw material into a floated residue on an upper layer, nutrients on a middle layer and settled sand on a lower layer. A barrier ditch (8) is interconnected with the pretreatment tank and used for filtering out the floated residue from the upper layer floated residue and nutrient middle layer in the pretreatment tank. One end of a sand and water separator (4) is extended into the bottom of the pretreatment tank and the other end is extended outwards from the pretreatment tank. The sand and water separator is used for sucking the settled sand on the lower layer to separate out sand and water. An INDEPENDENT CLAIM is also included for pretreatment of anaerobic fermentation raw material by employing the pretreatment system of anaerobic fermentation raw material, comprising: adding an anaerobic fermentation raw material into the pretreatment tank, adding water or refluxing biogas liquid to dilute the anaerobic fermentation raw material, cooperatively agitating diluted anaerobic fermentation raw material to settle and delaminating the settled sand by an upper agitator and a lower agitator, separating nutrients and floated residue in the anaerobic fermentation raw material into a floated residue on an upper layer, a nutrient middle layer and the settled sand on lower layer, filtering the floated residue from the upper layer of the pretreatment tank by a barrier ditch, and absorbing the settled sand on the lower layer of the pretreatment tank by using a sand and water separator to separate sand and water.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of the pretreatment system of anaerobic fermentation raw material.    Sand and water separator (4)    Pretreatment tank (5)    Upper agitator (6)    Barrier ditch (8)    Lower agitator (16)