The invention relates to a biogas digester cleaning machine for biomass straw and human and animal excrement mixed fermentation preparation. The biogas digester cleaning machine consists of a base plate, travelling wheels and a scraping device. The travelling wheels are mounted at the lower end of the base plate, the scraping device is mounted at the upper end of the base plate, and the scraping device consists of lifting air cylinders, a lifting stand, a rotary mechanism, a mounting column, a stabilizing mechanism, scraping mechanisms, a No.1 collection mechanism and a No.2 collection mechanism. The stabilizing mechanism includes an annular sliding rail, rotary sliding tables, a traction electric push rod, a connecting ring, support rods, an extrusion plate and a rubber strip. Each scraping mechanism includes telescopic support plates, No.1 limit plates, No.2 limit plates, push air cylinders, auxiliary plates and scrapers. The biogas digester cleaning machine provided by the inventioncan solve the problems of large labor intensity, low work efficiency, poor reliability, large potential safety hazard and the like in existing biogas digester feed inlet residue cleaning process, canrealize the function of automatic cleaning of biogas digester feed inlet residue, and has the advantages of high work efficiency, high reliability, high work safety, etc.