The invention discloses a method for industrial co-production of phycocyanin, spirulina polysaccharide and protein feed from fresh spirulina. The method comprises the following steps: (1), taking cleaned fresh spirulina sludge into an ultrasonic extraction tank; (2), uniformly stirring the mixed solution, and performing ultrasonic wall breaking extraction; (3), extracting the mixed solution for solid-liquid separation; (4), performing separation on an algae residue / grinding bead mixture by a filter screen; (5), cleaning and recycling grinding beads; (6), performing solid-liquid separation on the algae residue mixed solution again by a fine filter; (7), passing the combined phycocyanin extract through cross-flow membrane filtration equipment; (8), passing the supernatant in the previous step through 30 KDa ultrafiltration membrane equipment; (9), spray drying an ultrafiltration concentrated solution. The method has the following advantages that no chemical additive is used, physical wall breaking is conducted, pure water extraction is conducted in the whole process, the extraction cost is reduced, no chemical sewage is discharged, the method is environmentally friendly, and the application requirement of the natural and healthy product of phycocyanin is met.