The invention belongs to the technical field of organic fertilizer preparation, and particularly relates to a device for preparing a bio-organic fertilizer from biogas residue waste liquid based on straw, the device comprises a circulation box, a feeding pipe and a discharging pipe, the upper end and the lower end of the side wall of the circulation box are connected with the feeding pipe and the discharging pipe respectively, and a protective cover is fixed in the circulation box; the multiple scrapers are continuously matched for operation, solid waste is arranged, the smoothness of the solid waste in the conveying process can be improved, meanwhile, later forming operation is facilitated, extrusion forming of the formed waste is achieved after the solid waste is flatly laid and in the rolling process of the roller, integrated machining operation can be achieved, transfer is reduced, and the production efficiency is improved. And meanwhile, the overall processing fluency is improved, the fertilizer processing efficiency is improved, stable forming of solid waste can be ensured when raw materials are insufficient or mechanical faults occur, so that the quality of the bio-organic fertilizer is improved, meanwhile, when the raw materials are insufficient, an alarm can be given in time, shutdown can be conducted in time, energy is saved, and the environment is better protected.