The invention discloses a method for preparing an electroneutral amphichroic polyacrylamide flocculant. The copolymer flocculant comprises two structural elements of acrylamide and a lycine monomer (4-vinyl pyridine propyl sulphobetaine or 4-vinyl pyridine butyl sulphobetaine). The method is as follows: 40 to 400 grams per liter of mixed monomer solution is added into a reaction kettle; 0 to 1 mol per liter of brine saline solution is taken as a solvent; a mixed monomer is 1 to 50 weight percent of the acrylamide; the lycine monomer is between 99 and 50 weight percent; an oxidant of a redox initiation system is one of potassium persulfate, sodium persulfate or ammonium persulfate; sodium bisulfite is taken a reducing agent; the concentration of the mixed monomer solution is 0.03 to 0.48 percent of the mixed monomer, and the mixed monomer solution reacts for 1 to 48 hours at a temperature of between 5 and 50 DEG C; and reaction products are subjected to acetone precipitation, drying and crushing to obtain the amphichroic lycine polyacrylamide flocculant. The method prepares the completely electroneutral amphichroic polyacrylamide flocculant; both the molecular weight of the products and the content of the lycine monomer are easy to control; and the electroneutral amphichroic polyacrylamide flocculant has excellent treatment effect on both kaolin and ferric oxide waste water.